Does it happen often? What is the probability of providers going out with a hobbyist, before or after a session to develop, a repeat client? Is it rare? Are you too busy to go out or like Julia Roberts in Pretty Woman, don't want to get emotionally attached to clients? Maybe you've done this in the past & enjoy getting to know your clients and it helps further develop regular relationship and/or friendships.
As for me, I've met some providers who were very personable and enjoy hanging out every now & then. On the flip side I've invited a provider, who doesn't beat around the bush and asks for a donation, even after I've clarified that its just lunch. Certainly understand that time is money, you pay for companionship even if no sex is performed.
No right or wrong answer here, just a curious hobbyist who loves performing cunnilingus on beautiful women!