I must say I'm pleased that the game recognizes no-alarm+no-kills over use of continues.
Because that's how I usually play MGS games. Restart zone until it's a perfect sneak-through, captured the most relevant guards/items etc.. It's also a bit easier to handle than in GZ as it's more obvious where the "zones" for the continues are (like in older MGS games).
Being split up in missions helps with getting S rank in some parts of the game first try while still having the option to go guns-blazing in vehicle destruction missions etc (which would have ruined my no-alarm playthroughs in older MGS games).
However, being such a big game by itself, perfectionism will ruin me lol. Takes ages for me to progress especially as I also want to collect everything and do the micromanagement stuff "I'm missing some minor metal for the next platform, well, maybe I should capture this base in free roam while I'm at it..."