Not so much stoopid as impractical for the WG. She has other customers too, let alone a life outside whoring that involves commitments. I don't see WG's offering £30 taster's SAAFE forum would meltdown!
What is a 15 minute appointment, if not a 'taster' session, in all but name? It feels more like a game of semantics to argue the toss between defining the difference (or lack there of) between a 15 minute 'quickie' and a 15 minute 'taster'? From personal experience, WG's offer short appointments, both for personal preference and borne out of an appreciation of some of the risks punters take when booking someone new. Accordingly, quickies are explicitly intended to offer the punter an opportunity to 'try out'
their chosen service while reducing the unavoidable financial risk and minimizing the amount of time potentially going down the drain!
Rather than 'impractical'
as you put it, quite to the contrary in my view, a savvy WG would consider it a 'job well done'
if, as suggested by the O.P, a punter expressed the desire to extend their agreed 'quickie' appointment. Such a scenario is; 'win, win', from a WG 's point of view, then having the option to extend (and accordingly earn a higher fee) or, if already time committed and unable to accept the offer, is able to secure a follow up appointment ie repeat custom, one of the main objectives of offering 15 minute quickies in the first place!
As a WG, your view on the O.P's idea, seems to me, topsy turvy. When a WG is with a punter, whether it be for 15 minutes or 15 hours, in my humble opinion, the WG's focus, attention and priority, belongs IN that allocated time, the very thing the paying customer has paid to secure! Thus, your suggestion that the O.P's idea is 'impractical' based on the assumption such a request is inconsiderate to the WG's life OUTWITH her present engagement is irrelevant, most certainly should be to the punter (having been made to feel as such by the manner of the WG) What other commitments and/or customers a WG may or may not have to consider or contend with is NOT the concern of the punter and part of the job of the WG to maintain a complete distance between the two. In reality, any decent WG's are/should be adaptable and open to accommodating the punter ie, PAYING CUSTOMER in what ever way is requested (obviously within safe and decent boundaries)