I pay regulars the same like it would be our only meetup during trip and have habit of fixing compensation before meeting. With guys you see regularly keep in mind that you will be stuck with price i.e , if you use to pay him , say 3000 but once , being extremely happy you gave him 3500 or 4000 , next time he will be expecting that 4000. I learned this lesson and as result was forced to drop few regular guys who at the same time become too greedy and slacking with duties of companionship .
as for frequency , it may depend on guy and how you feel with him. On my last trip in Bangkok part I was alternating two boys and it worked extremely well for everybody although each of them had one 'weaker day ' , when it was clear to a degree they rather be somewhere else.
I never make promises " I will see you tonight (or tomorrow) again " if i 'm not 127.84% sure that it will be a case. If they ask first 'want about tonight " I either tell them ' no' as it's easier to change that to 'yes' than other way around or tell them " not sure , I will let you know before xxx hour" and then do it