clearstream
(He, Him)
As by now many posters are aware, game rules are largely constitutive. By this is meant that the distinctive play of the game cannot be performed or engaged in, unless these rules are in force. One implication is that if you change the rules, you change the game.In another thread there's been some recent debate regarding just how closely DMs adhere to the rules as written* for the system they are using. The specific example was 5e D&D, but the question can apply to pretty much any RPG: do you stick to the rules as written and treat them more like laws, or do you treat them more like guidelines and change/add/delete rules you don't like. And in either case, why?
* - including errata, Crawford tweets, updates, revisions, etc. depending on system.
Me, I'm 'guidelines' all the way. If something doesn't make sense to me as DM I'll change it to something that does; and if something just gets in the way of playing the game (e.g. 1e initiative RAW) I'll find a way to rebuild and simplify it.
Note that I'm not referring to changing rules on a whim, or to being inconsistent with rulings in an ongoing campaign - those are different issues. This is more to do with how you approach RPG rule-sets in general.
Thus a "guidelines all the way" approach translates to a statement about the game you intend to play. It isn't that you do not follow rules - after all, consistent rulings are not readily distinguished from written rules - but that in view of what would be constituted by certain written rules, you aim to bring those written rules into accord with the way you aim to play. (Frex by novation.)
Another motive may be one of betterment, perhaps with efficiency in mind: you aim to play the game in the same way as would be constituted by the written rule (or at least, that is not at issue), and you use a modified form of the written rule that achieves that same ends in a better way (here I am talking about the method or process by which the ends is met, not the ends themselves.)
"Better" could well include simply that you don't care to learn the rules. Setting aside that you can scarcely say whether or not you are following rules you do not know; this could still be about learning the written rules well enough to apply them repeatedly and reliably. In this case, you might be aiming to achieve play that is impressionistically similar to play-by-the-written-rules, with no particular concern to achieve that play precisely.
Perhaps all apply. You aim to play in a modified way that you see as better, and you aim to effect that play in a modified way, too. In either case, it suggests taking ownership of play and not yielding to authority. Resisting norms as might be reinforced by "Crawford tweets" etc. In a way therefore, I see your question as one of - to what extent does your group feel compelled to adhere to norms? Seeing as consistency with rulings is still valued - it seems to me that it is not rule-following itself that is at issue - but adherence to external norms.
Contrast an OP with similar concerns as yours, but that expressly embraces inconsistency!? Answers to the questions raised will come out very differently. Chances are, many respondents will not believe or not fully accept that consistency really is being resolutely set aside: they would assume varying levels of consistency, rather than no consistency at all.
If a central job of game rules is to constitute the game, another is to do so on every occasion that the game is played. Certainly groups might not be concerned to play the game exactly the same way on different occasions (if they don't follow written rules, that outcome seems likely) but I believe they do not intend to play that game in utterly different ways on different occasions! We couldn't even in that case say which game they are playing, as each would be a unique instance. However, supposing that was indeed a group's purpose, it would be a rather radical consequence of your opening thought, and one which you seem to rule it out with your closing comments on inconsistency.