Should a level be solvable on the first attempt?

[rockdet]

To answer ajmiam's question about Old Frog: When I opened it for the first time (way before CCLP3), I played along with the map. Those kind of levels are obviously not meant to be played casual, therefore not suitable for a CCLP in my humble and honest opinion. I messed around for 2 hours WITH the map, and I was still going absolutely nowhere, so it's safe to say it's pretty unreasonable to expect casual play from someone through this whole thing and/or expect someone to find the solution without a map on the first try. Though I understand the idea and the concept, it should belong to the individuals ready to take on the challenge itself.

As a perfect illustration for what I mean there, Cloner's Maze (if not for the fact that it should have been untimed) can be figured out on one's first try, and remains to the day one of the greatest puzzles ever designed.