The key word here is 'try'. The one problem I notice at times with this game is that you can never be too certain about what you're gonna block, specially with units that only have that 1 block count. It doesn't help that if you farm one map ad infinitum, mobs look like they move alittle in their pathing, so its just up to lots of experience with that one map to know when to place units to block that one mob you needed blocked.
It is painful.
I can see why, but there is always room for that one niche unit that could prove useful in future events. Or if your name is Black Karma you get used against the big bad unit of that event.
Not sure if its good to have more luck in getting skill ups than cost reductions, but I'll take what I can get with these farm events :P