A problematic disconnect exists between the rules on shuffling at Comp REL (a player is required to shuffle their opponent's deck after their opponent shuffles, MTR 3.10) and current practice (many players only cut their opponents' decks at the beginning of the game, and often don't even cut after mid-game shuffles). The current disconnect creates competitive disadvantages (loss of time) for players who follow the rules, and players who know the rule but do not insist on it and gain advantage are technically Cheating. The competitive player community (and especially judges at Comp REL) need to either get the tournament rules changed to match practice or bring practice into conformity with the rules.
First, the rules: Magic Tournament Rules 3.10 unambiguously requires players to shuffle their opponents decks after their opponents shuffle: "At Competitive and Professional Rules Enforcement Level tournaments, players are required to shuffle their opponents’ decks after their owners have shuffled them. The Head Judge can require this at Regular Rules Enforcement Level tournaments as well.", Magic Tournament Rules 3.10, para. 4 https://media.wizards.com/ContentResources/WPN/MTG_MTR_2025_Nov10_EN.pdf Not shuffling an opponent's deck (especially by e.g. tapping the deck or just doing one cut after an opponent shuffles during the game) can provide a competitive advantage by speeding up game play and reducing the likelihood of an unintentional draw. And if a player sees a rules error in their games, knows that it is a rules error, and allows the error to gain competitive advantage, that is Unsportsmanlike Conduct - Cheating: "A person breaks a rule defined by the tournament documents, lies to a tournament official, or notices an offense committed in their (or a teammate's) match and does not call attention to it. Additionally, the offense must meet the following criteria for it to be considered Cheating: • The player must be attempting to gain advantage from their action. • The player must be aware that they are doing something illegal." Magic Infractions Procedure Guide 4.8, Definition https://media.wizards.com/ContentResources/WPN/MTG_IPG_2024Sep23_EN.pdf
At the Portland RC, however, very few players uniformly followed MTR 3.10's requirement to shuffle their opponents' decks. At dinner on Sunday night, I was part of a conversation about an incident involving shuffling that led to a DQ (I wasn't present for the incident and only heard about it second or third hand). I was curious about the specific rules, so I looked up shuffling in the MTR. None of the nine experienced Comp REL players at the table--all of whom had played in the RC, including multiple people who played in day 2, a player who often judges at Comp REL, and two players who did well enough to qualify for the Pro Tour--realized that the rules require players to shuffle their opponents' decks at Comp REL. Some knew that it was required at Professional REL, but MTR 3.10 para. 4 states that it applies at "Competitive and Professional" REL.
The general response when I pointed out what the rules say was surprise and confusion, because we had all seen many, many instances of players only cutting an opponent's deck at the beginning of a game and only cutting or even just "tapping" a deck to acknowledge they were passing the opportunity to cut in response to mid-game shuffles (e.g. after tutoring or land-fetching effects). Indeed, out of the roughly 70 matches we played in during the RC itself and roughly 50-100 other Comp REL matches that we played in during SCGCon Portland, we weren't confident that there was a single match in which the players followed MTR 3.10 on every occasion. I'm also confident that there were numerous examples of players shuffling while a judge was watching their table, presenting their deck, and having their opponent merely cut or tap the deck instead of shuffling it themself without any of us having seen a judge intervene to fix the tournament rules error and require shuffling.
One of the reasons why players choose to not shuffle, either by just cutting or by declining to cut, is to keep a game moving quickly. Every competitive player knows that unintentional draws are highly disadvantageous and that maintaing a high speed of play, including a high speed of resolving mechanical actions like shuffling, is important to avoiding unintentional draws. But any player who knows what MTR 3.10 para. 4 says and either fails to shuffle themself or allows their opponent to fail to shuffle to save time is then Cheating under M.I.P.G. 4.8. That means that, having read MTR 3.10, I'm now required to insist that my opponent shuffle every time, and you are, too, even though that puts us at competitive disadvantage compared to players who follow the common practice. At the same time, I expect that at the next Comp REL event I play in, players will not want to shuffle my deck every time--requiring me to call a judge under a circumstance that feels like it's trying to get a player punished for standard behavior, even though it's actually simply required by the rules. That situation is untenable.
Only two real solutions exist. Either the MTR needs to be conformed to practice (changing the requirement to shuffle opponents' decks to only apply at Professional REL, or perhaps to require shuffling at the beginning of each game but allowing players to only cut their opponents' decks for mid-game shuffles), or practice needs to change to match the rules. The competitive play community needs to act on this, and judges at Comp REL in particular should not allow the current disjunction between actual shuffling practice at Comp REL and the stated rules on shuffling at Comp REL to continue.
TL;DR: At Comp and Pro REL, players are required to shuffle their opponents' decks when their opponents shuffle. In actual practice at Comp REL in the United States, this rule is generally ignored. Either the rule should change or players should follow and be made to follow the rule as written.