In my heart of hearts, I'd still be a twice-a-week bench presser, but the demands of life and my immediate physical requirements have altered my stance on my approaches towards the main lifts.
I've gradually leaned into @MarkKO's approach to the "main" lifts: I think once a week is fine if eating, sleeping, and overall recovery habits are properly dialed in. I think it's possible to make measurable progress if you handle things on the accessory front. I still think frequency is relevant, but a lot can happen with enough rest and consistent eating habits. You can get away with less-frequent benching if you take care of your benching muscles.
Ample work with front and rear delts, upper back/lats, and hips. I prefer a bodybuilding approach, i.e., high volume and low fatigue. Eat like you're aiming to max out, but use a sets-across approach to maintain your confidence and your recovery reserves. I have my best days when I prep muscle groups that'll aid with hip drive and a controlled (but not necessarily slow) eccentric a few days in advance. I think hip drive and lower-back health are related. Work your hip flexors.
I'd keep a lazy eye on Hanley's rep/set schemes. He's a math whore, but there's also an autoregulated intuition that makes sense if you stare at his load progressions long enough.
Lastly, everything's connected; energy leaks come from the oddest places. Take advantage of all the machines at your disposal that'll strengthen your ball-and-socket joints. Stick to your own timeframes, enjoy yourself, stay safe, and have some good metal on hand.
I've rarely used an actual Roman chair (Captain's chair?), but I think you're right about the purpose of the obtuse back angle. More ROM for the abs, and more ROM for the hip flexors.- Ended with sightly bent leg raises (not knee raises) in one of those fucking awful Roman chairs where the thing is angled back like 30 degrees, maybe more, presumably so that one can get a huge ROM but which really just forces one’s back into a giant arch.