A working paper circulated this month by the University of Nevada, Las Vegas's International Gaming Institute reports that bettors who placed wagers through a two-tap bet slip completed 31% more betting sessions of 30 minutes or longer than users of a five-tap slip, across a 14-week observation window ending in March 2025. The finding held after controlling for stake size, sport, and device, and it reverses the common product assumption that fewer taps mainly help conversion on the first bet. The study's authors argue the effect is a session-length effect, not a signup effect, and that it compounds over a betting career.
What the Study Actually Measured
The sample covered 4,812 active accounts at three licensed U.S. sportsbooks operating in the same state, each with a similar menu of pregame and in-play markets. Researchers instrumented the bet slip — the sequence from selecting a market to confirming a stake — and logged every tap, scroll, and back-navigation. A "two-tap" slip was defined as market selection followed by stake confirmation with no intermediate screen. A "five-tap" slip required at least five discrete interactions: open slip, select market, choose stake, review, confirm.
The dependent variable was not handle or hold. It was the count of sessions lasting 30 minutes or more, a threshold the authors chose because it sits near the median session length in the sample (27.4 minutes) and because shorter sessions are dominated by single-bet, single-event visits that say little about sustained engagement.
Three things stand out in the methodology. First, the authors excluded accounts opened in the 30 days before the window, removing the signup-conversion confound. Second, they ran the comparison within-subject where possible: 1,106 accounts experienced both slip designs after a mid-study A/B rollout, which lets the paper compare the same bettor against himself. Third, they weighted by session, not by user, so a small number of heavy bettors could not drive the result.
The headline coefficient: two-tap users averaged 5.8 qualifying sessions per 30 days against 4.4 for five-tap users, a 31.8% gap that narrowed to 24.1% in the within-subject comparison. That narrowing matters. It suggests roughly a quarter of the raw effect is selection — bettors who already bet more often may have been routed to the faster slip during the rollout — while the remainder is behavioral.
The Tap-Count Threshold
The paper tested three-, four-, and five-tap variants and found the engagement gain was not linear. Moving from five taps to four produced a 6.2% improvement in qualifying sessions. Four to three produced 9.7%. Three to two produced 18.4%. The authors describe this as a "cliff" rather than a slope, and they are careful to note the two-tap condition is the only one where the review screen disappears entirely. Their interpretation is that the review step, not the tap count per se, is doing much of the work — a distinction with product implications that go beyond tap-count optimization.
Why Fewer Taps Might Extend Sessions
The mechanism the paper proposes is friction-as-interruption. A five-tap slip inserts a review screen between intent and execution, and that screen arrives at the moment a bettor is most likely to reconsider. For single-bet recreational play, reconsideration is often harmless or even protective. But in a multi-leg or in-play context, the interruption breaks the rhythm of a session and, the authors argue, nudges bettors toward ending the session rather than continuing it.
There is a competing explanation the paper does not fully rule out: faster slips may simply allow more bets per unit of time, and more bets per session mechanically extends session length. The authors address this by controlling for bets-per-session and find the effect persists at 19.3%, though with wider confidence intervals. That residual is the interesting number, because it implies the slip design changes not just throughput but the decision to keep the app open.
A third possibility is novelty. Two-tap slips were new to roughly two-thirds of the sample during the window, and novelty effects in engagement metrics are well documented. The within-subject group, which experienced both designs, showed a smaller effect — consistent with at least some novelty decay. The paper's own sensitivity analysis flags this and recommends a 12-month follow-up.
The Regulatory and Responsible-Gambling Problem
This is where the finding gets uncomfortable. A design change that reliably extends session length by roughly a quarter is, from a public-health standpoint, a design change that increases exposure. The UNLV team is explicit about this: they note that session length correlates with both handle and, in problem-gambling literature, with harm indicators, and they call for operators to pair slip-speed improvements with session-limit prompts rather than treat the engagement gain as a pure win.
The study did not measure harm outcomes, and it should not be read as evidence that two-tap slips cause harm. What it does establish is that the design lever is real and directional. State regulators in markets with mandatory session-timer or deposit-limit rules may find the paper relevant to how they think about "speed of play" as a product characteristic rather than a neutral interface choice. New Jersey's Division of Gaming Enforcement, which has taken an interest in interface-level design questions, has not commented on the paper.
There is also a competitive dimension. If the effect holds, sportsbooks that keep five-tap slips are leaving qualifying sessions on the table, and the pressure to shorten slips will be strong. That pressure will arrive at the same time as responsible-gambling obligations, and the two will not always point the same way.
What the Numbers Don't Show
The paper does not report hold or margin by slip type, which is a meaningful omission — a session-count gain that comes with lower margin per session would be a wash. It also does not break out results by sport, despite collecting the data, and in-play bettors may behave differently from pregame bettors in ways that matter. The 14-week window is short for a behavioral claim, and the three-operator sample, while matched on market menu, may not generalize to operators with different cash-out or parlay-promo configurations.
What to Watch
The obvious next test is a longer within-subject design with hold and harm indicators included, and at least one operator is reportedly running it. The more interesting question is whether the cliff at two taps is a genuine behavioral threshold or an artifact of what the two-tap condition removes — the review screen. If it is the review screen, then the engagement gain is really a gain from removing a confirmation step, and a three-tap slip with a non-blocking confirmation could capture most of the benefit while preserving the pause. Nobody has tested that variant yet, and the paper's own data suggest it would land somewhere between the 9.7% and 18.4% marks. Until someone runs it, the industry has a clean result and an unclear mechanism, which is a familiar place for iGaming research to sit.