You don't have to skip all collection quests, just skip the ones that have a drop rate of less then 80%. When the drop is 80% or higher it is almost like a kill quest. I remember there are a couple quests in hellfire where you have to kill voids and collect 40 shards, well every voids always drop 1 some drop 2 and some drop 3. When i was 5 boxing i did that quest cause it wasn't a low drop rate, i know that i need to at least kill 200 voids, but i knew the voids where easy kills and they also drop motes of shadow, which a primal shadow (10 motes) go for at least 35g on my server. So i got about 50 motes and made 175g. I collection quest that i did skip even though it wasn't a drop quest was the zep parts omg by the time 3 of my 5 toons got 40 parts i was falling asleep.