For me, personal training took more time.
When I started out in group exercise, the longest training that I had was a 56 hour in-house training for a small chain of fitness centers in my state. In that 56 hours, we had book learning and practical experience. After that, we had an all-day exam, both written and practical. Nothing I’ve done for group-ex since has come anywhere even close. I studied for about 8 hours for AFAA plus the one-day AFAA course itself. NDEITA was done in one day. YMCA group fitness leader was one day. YMCA fitness instructor was 2 days.
Personal training, I took about 100 hours to study for the ACE exam, reading it cover to cover and making my own flash cards. I already knew much of the anatomy and physiology from group-ex, so the bulk of the study was on assessment and individualized program design. Then it took me another 60 or 70 hours to go through the NASM book cover to cover.