Touching up several tattoos at a time?

I have 4 or 5 medium tattoos (the largest being slightly bigger than my hand) that need touching up. Is it likely to be possible/practical to get it all done in one session? How long do touch ups typically take? I understand it's different for every tattoo but I'm hoping for a ball park before i waste an artists time and also to budget. Also one of them was done by the shop I intend to go to the others are from various shops, are most artists comfortable touching up other peoples work?
Touching up several tattoos at a time?
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