I have seen repeat visits go one of two ways, as Al has discussed above, they can become complicated with feelings, if that happens, the sex usually gets fantastic, because it's not just fucking, it's more emotional as well as physical. For the record, this happened to me once, and while it was the best sex I ever had, it was also incredibly painful when it became obvious it wasn't going to go anywhere, the spark dies and the emotional connection is lost. I saw her once earlier this year after my retirement was over as an SP and the sex was still good, but it's not the same. I won't see her again. My divorce was less painful than this split.
The second way settles into a friendly but ultimately business like relationship where you have some sort of connection, but it never gets complicated with "love". The sex can get really fantastic here too, but not to the depth and breadth as above. It can be ruined by a bad session and it's best if both sides agree to be completely honest. If she's in a bad mood, don't see her! If you are in a bad mood, don't go! It's rare and don't take the chance of fucking it up. I have one of these as well, but she's in Alberta not the lower mainland, but every time the sex is as good or better, in fact, after a long break it's often even better as we both know each others buttons very well. Absence makes the dick grow harder so to speak.
In both cases, the sex has to be as good or better over time. If the sex is getting worse after repeat visits, stop repeating already, what are you a masochist? It should only take one shitty session to fall off your to do list forever, unless there's a damn good reason. And if any money grubbing, rushing, taking you for granted, last second cancellations, asking for loans, etc. start showing up, it is time to bail.