Yes, schlep isn't used for tasks. It's used only for journeys. The connotation is that a particular trip is going to be long, painful, tedious, annoying, diffic

Yes, schlep isn't used for tasks. It's used only for journeys. The connotation is that a particular trip is going to be long, painful, tedious, annoying, difficult, etc. It is not used for tasks that don't involve physically moving yourself or transporting something.