Depends. If you're happy with half hours, then two half hour punts with different SP's is better than an hour with one, even if it'll be a little more expensive. The law of diminishing returns.
I personally don't like half hours (parlours excepted) as I'd be too rushed. I wouldn't feel as though I'd fucked her thoroughly enough. Only ever go for one pop, but I can go for the hour with a little 'management' of the punt.
tcm