Success Training Twice a Day?

For those who have had success training twice a day (same muscle group- strength in the morning, hypertrophy evening), what routines/ workout outlines (exercises, sets, reps) did you find most effective?

I would assume (bad thing to do, I know) that for recovery purposes, it might be a good idea - though not necessarily the best, depending on your goals - to train antagonistically: workout A in the morning, B (antagonistic pairings of workout A) in the evening. I want to eventually train twice a day and might start with this setup when I eventually do.

I personally recover faster when I train the antagonist within the next 24 hours of the first session.

I have read that you should only train the same muscles in both workouts: have workout 1 in the morning be a lower rep and strength oriented thing and workout 2 in the afternoon a higher rep scheme. Don’t know if that is what is completely ideal, but there have been many people here who have said that.

I tried it for about 2 months.

I followed the HST protocol: 2 brief (30 minute) full-body workouts a day, 3X per week.

Seemed to work well.

I just got done doing a couple months upper/lower split, It was exactly what I needed after doing a body part split for like 5 years. My strength and hypertrophy went way up, and I felt generally “better”. I would do twice a day training, heavy weight compound movements in the morning, lighter weight iso movements at night. Workouts were shorter but I felt like I got more done, I plan on cycling that in with a split routine now. (when im on split I only do single sessions)