A bowl that size will usually give 6-8 good hits (15-20 seconds). After the first three take a paper clip (bent so it's straight) and stir the weed to expose stuff that wasn't exposed earlier.
Yeah, 2-3 hits on a standard whip bowl, half full, isn't much. Too hot a temp will cook your herb too quick, and you do have to stir the bowl to get it all exposed to the hot air stream. It's easier to make sure you get it all vaped if you load a smaller amount. It will decrease the size and number of hits, for sure. It's a trade off. OTOH, a large quantity in the bowl means having to hit spent herb repeatedly to make sure you're getting to it all, and that ends up compromising the taste toward the end of the bowl.