A recent study had experienced male lifters train a muscle 5x per week or only 2x per week for 8 weeks [Zaroni 2018].
As you can see, training muscles 5x per week gave superior results.
Very probably, the better gains came from spreading the 15 sets over 5 days, which enabled them to do more of their sets ‘fresh’: on a separate day, which allowed them to lift more kg’s in total muscle work.
And to actually recover on a workout-to-workout basis.
Compare that to squeezing all these sets in 2 days: how many quality hip thrust reps can you still do after 6+ sets of romanian deadlifts, squats, and glute kickbacks?
Right. And a more recent study confirms this theory: ~5 sets to failure per workout in experienced lifters give maximum muscle growth [Barbalho 2019]. Heck, doing more than that gave *less* muscle growth.
However, *not* going to failure every single set probably allows you some more sets per workout that you can maximally recover from, probably between 9 and 13 sets.
Just like how you wouldn’t eat a 3000 kcal diet in a single meal per day, you shouldn’t do all your weekly training volume in a single day.
Rather, spread the calories, or your sets, over the week. Your intestines (and muscles) will thank you for it.
Specifically, let’s look at how the average woman trains her glutes: 4-6 different exercises with 3+ sets per workout. Ouch.
Spread it over the week. Don’t heap it on the day.