Depends on the service, of course...but generally, agencies are MUCH higher-volume. Think anywhere from 2-8 guys per day. And I did not always have time to shower...clients were late, overstayed, the agency told the next guy I'd be done by 5pm even tho the last guy got there at 4:30, etc. I was in such a hurry sometimes...it was all I could do sometimes to just reapply lipstick and smooth the bedspread...
Since the girls can't screen, some of the hobby world's most undesirable clients can get appointments. Might mean that the guy before you was a complete asshole, and that could affect your session.
I didn't have such a great attitude toward clients when I was an agency provider. I always felt worn out, overworked, sore, etc. I did not look forward to appointments for any reason EXCEPT the smell of green paper. In fact, I'll even go so far as to say that I resented most of my clients, as the demands on my body and time seemed disproportionate to what I considered reasonable.
Being independent...whole different world. I see men I'm comfortable with, and in most cases, actually like. I'm building my reputation/brand, so I have more of a stake in my level of service...I'm more open to actually enjoying myself. And, I rarely see more than 3-4 per WEEK.
There is a price to be paid for convenience. Just have to determine if it's worth it for you.