Many women don't cum during intercourse, in my experience not many, so pounding is not the path (for you maybe) but not for her.
Most respond to a gental touch, and very nice subtle daty, some are a little more sensitive, and will take 8 to 10 minutes, others, can take 20 minutes (now that is commitment).
I would also suggest 30 minutes in most cases is not enough time.
Noting as well what time do you visit ... if you are late afternoon or evening it's likely the girls have had, 1, 2 maybe 3 orgasms already if the are able, so no matter what you want, they are spent for the day. Some only orgasm once a day ... some only a few times a week.
I would also recommend you ask, have you had an orgasm today?
My most successful visits are always early, say 12pm or 1pm, and try and be their first orgasm of the day ... so much easier. Note as well, that some girls don't orgasm at all, some in 3 to 5 minutes and others 20 minutes or more ...
So many variables .... my advice, go early, book for one hour, get on your knees and let you tongue do the work, a nice reverse massage to start for 10 minutes or so allows them to relax.
Note as well, for clean girls, you can really move them along by licking their anus and ass, some really respond to this, not much action there for many. But, only for girls who shower after every visit ... I'm sure you understand why, cleanliness is a must for this level of commitment.
But pounding ... highly unlikely you will get the desired result.
Hope this helps ...