unless your girl cums like a dude. as in one big o and shes done.
you learn to get her til shes almost there, shaking and pulsing, then take the opportunity of her max horniess and do your thing, then reward her by getting her off all the way.
works great for us, at least.
if i let her get off first, shes just on cruise control. shes done. thats no fun for anyone.