I did that loads in the early 2013-late 2014 period and an awful lot of projects fell though. Honestly speaking though, a lot of them were probably doomed from the start because I'd assign higher priority to the ones I wanted to work on most. There's not a lot of point if it's so low on your list that you nearly ignore it. I'm trying to keep to no more than 2 active projects at a time, the rest can be all kept as ideas, concepts, sketches, etc. until I know I'll be able to dedicate something to them.
kkots
I have no problem keeping things fresh within one project. If a project is large enough there are always interesting things to do with it.