@Ahribar, I'd stay far away from #5, then...
Anyways, your notebook. Some of the levels, and your descriptions of them, remind me a lot of my early notebook levels.
I've passed (so far) all but #9 and #10. As for #9, I'm completely stuck; I can't offhand see how to cut the 15 or so seconds you need off of your route. #10, admittedly, I haven't looked at as well as I could have.
Interesting levels, I must say. First few seem a bit easy, but it's the same with my notebooks. I think my route for the last 1 of each task level was quite a bit more complicated than you intended, but I couldn't figure out another way to pass it. Still, an enjoyable set. Nice work.
As for "Why Bother?" -- The Needy Bunch and Oh Well are two of those levels that look fairly simple but are giving me a LOT of problems. They are probably two of my favorite levels in the set.
The one gripe I have, and Ahribar hit on it already, is the number of hidden traps in the levels. Especially the icicle trap and the boulder trap: those freak me out when I can't see them coming. (That, and I rarely, if ever hide traps; I usually keep at least the activation button exposed when the trap is not.)