Instant respawns happen quite a lot. Most of the time it is rather annoying. I
guess only for cashmobs instant spawns are ok. Though sometimes, it is nice to
have an instant spawn on a blocker, since then you know you have plenty of
time, ie full respawn cycle, to kill whatevr is behind the blocker.

Nonetheless, I would suggest that a minimum spawntime of 15minutes be
implemented, and maximum would remain as is. This would give plentiful time to
fight whatever the blockers block.

++glaurung