From playing Maya's Mission for a short time (in demo/unfinished form) this might be my consideration for "most efficient use of RenPy in an H-game". Mochi, the dev, has a great grasp on "keep it simple" and maintaining project quality towards providing a parody H-experience.
Maya's Mission is essentially an Ace Attorney parody game with H elements. Mochi has created a good gameplay loop of small tasks for the player to do while checking a scanner that shows Maya's actions that keep the player guessing (or seeing) lewd situations she's in.
I haven't actually played Ace Attorney other than years ago on a buddy's GBA, but it seems that the characters are written and acted well for the "world" they exist in (with the note that something is causing excessive lewdness). As far as graphics go, sprites edited based on actual game sprites do well here. Usually parody games that follow the original graphics drop the ball somewhere, but so far so good with Maya's Mission!
The lewd content is surprisingly good for being simple. A little bit of RenPy animation goes a long way and after browsing through the game's files I can tell there's been thought put forward to hiding and showing elements in the scanner. There's clear build-up and it keeps the player engaged. That, plus interacting with characters leading to unlocking cards, makes me think a good loop of H-content will continue.
Seems like the NTR tag is dividing some people in the thread, but I'm a neutral ground here since I generally dislike the NTR tag. For me it seems more like Phoenix and Maya have a platonic relationship, but even if it's intended to be "true" NTR, it didn't grind my engagement like more hardcore NTR stuff would. It feels more weighted on exhibition. To each their own. I wasn't turned away by it, so take that as you will?
As far as gameplay goes, a few quality updates could be made (and some seem to be on the way). The scanner needs a function to avoid missing unseen frames, and a gallery function should be somewhere. It would be nice to have a day-select from game start incase people want to re-experience a day without playing from the beginning or using loads of saves. A hint (or maybe an item you can use?) at how many cards are left to collect on a day-to-day would be nice to not accidentally skip side content.
The story seems to not have dividing paths and Mochi posted that there will be only one main ending. That seems fitting. As I said previously, the game's story loop seems simple, which is a good thing for a RenPy game. Too often devs will try to shoot for the stars and never leave atmosphere. The content here is good, keep it up.
At the moment the game is in demo form and I'll be back when it's finished. Very promising!