Request stops do not have dwell times so therefore as an example from Holyhead to Llandudno Junction you have 8 request stops, the dwell time including stopping and dispatch is about a minute all told so therefore the TOC saves 8 minutes track access fees. You do have dwell times at stations to compensate.
This isn't a standard for all request stops, there are many request stops in Devon and Cornwall where 1/2 minute dwell time has to be allowed. Ultimately it depends entirely on the location and therefore the planning rules set - which stipulate how much dwell time to give.
In North Wales where stations have no dwell time, the timings are for the time the train stops and then starts off again, therefore if dwell times were allowed which would most likely be 1/2 minute, the saving in track access fees would only be 4 minutes, not 8. (1 minute dwell for a request stop would be too much - especially as if you then don't stop you could end up early at the next request stop and then if you don't stop there early at the one after, this being the reason for Public/WTT differentials at request stops.)
Ultimately however the journey time will allow enough time to have stopped at all of the request stops, through various allowances.