i am gravitating toward pulling with much smaller amounts as opposed to larger. it is more comfortable and takes less time to complete. for a marathoner like me, it breaks it up so if i want to speak or get interrupted and have to answer a Cell Phone (yuk), i am not wasting as much oil. i think it is better to do two ten minute pulls than one thirty minute one. there is something about that fresh injection of oil immediately after spitting that says "this is really good" to me. it just seems right. it is palpably more effective as well.