I did 3 days in a row 6-8 hours each day all on my arm. It healed fine and i'm very happy with the result but jesus christ do I never recommend that for anyone lol. I was so drained by the third day that I didn't feel like speaking and just wanted the tattoo to be done.
no,as long as you are up to it,
like you feel good,eat well,sleep well,pre-hydrate,etc,etc the day & night before & day of.
most important is to mentally prepare.