Hi
I am not an artist but asked him this same question. He is often booked upto 12 mths in advance and can afford to turn down a lot of work.
He worked on my back in a lot of late sessions after closing time.
He stated the key issue was whether the work excited/interested him – if he was stoked up on the job he would find time to squeeze it in.
Other factors he mentioned were;
Client’s attitude (ie don’t have a bad one).
The flexibility of the client with regards to times.
General rapport – if he gets on with a client it is easier to find that extra energy to work on them.
I guess every person is different some are money only, some are art orientated or a mixture only way to find out is check the artist out and see if you click or not (if you are looking for repeat or extended work that is).
Take Care
Matthew