So around 15 years ago I started sitting in on RPG sessions as a third party to directly observe how people interact with the rules, primarily with 3.5, since that was a game with a very strident RAW community, but also with other games. The results were very interesting, though it was a totally unscientific look.
Essentially, even GMs who run games “by the book” exercise enormous discretion about when and how to use various rules to the point where a declaration of RAW play is much less a predictor of how the rules will be used than things like the genders of players, the characters they’re playing, the presence of miniatures, relative rules mastery, or the current fortunes of the group at the table.
When players were not men, male GMs and fellow players were more likely to either encourage the most basic form of a mechanic (3.5–ordinary test against DM selected DC instead of a detailed subsystem) or use the rules as a medium for bullying and overbearing. Character classes that are traditionally seen as main characters were generally given preferential treatment by having people make sure they got beneficial rulings, which is why even though the cleric was the most powerful 3.5 class, clerics were rarely impressive in play. Relatedly, in most games, sorcerers were, hands-down, better than wizards, with the exception of players of wizards who could deploy the rules with expertise.
The presence of minatures made position-based abilities far more powerful. This was notable because when there was a map, rogues used sneak attack so much more often that they were basically a different class–without a map, the DM says no.
And of course, adult GMs are traditionally soft-hearted when it looks like the players are having it rough.
If you play D&D, don’t play a cleric, press for minis if you’re playing a rogue or anyone who has special abilities with a mount or zone controlling stuff. Favour intuitive fire-and-forget abilities over optmized stacked stuff if you think the DM will mess with your plans. If you’re a man, don’t “help,” just say you’re available for help but will wait for other people to ask. And if you’re hurt, ham it the fuck up with your pain and tragedy.
Lots of this can apply to other games, of course.