When you attempt to teleport you have a chance to end up off target:
Off Target: You appear safely a random distance away from the destination in a random direction. Distance off target is d% of the distance that was to be traveled. The direction off target is determined randomly.
My question is what 'appear safely' entails, and what directions are allowed? Can you end up in the middle of the sea (assuming for example, that you were targeting a coastal site)? Can you end up high in the air, or in a cave deep underground? Can you appear in any other inhospitable enviroment that can kill you almost instantly?
Or does even a failed spell have some security measures installed, and even if you appear off target you appear on ground level, with no risk of falling, drowning, being crushed etc.?
The spirit of "appear safely" is that you end up in an area that can sustain you, even if off target. Take into account and that "similar area" is on the table as being a worse result than "off target", so it should not be worse than a similar area. That all being said, if the players are obviously gambling, my attitude toward "off target" changes a little bit. If there is not "safe area" have the teleport return the caster and pals to the place the spell started, maybe rotated in a different orientation.