I find that I can easily reach my peak high without too much problems. Probably about bowl 3 or so. And after that, all I am doing is lengthening the high. That usually only requires a hit or two out of the bong to keep the buzz going, every 10-15 min.

Granted I dont usually follow this, and end up smoking 2-3 more bowls out of the bong after Im peaked... just kinda happens. I get so high that I forgot im so high.