[Stardouser]

I would say they should last for about 20 minutes after a decay-triggering event occurs, such as switching classes or logging out.

Assuming you do not switch classes, what is the limit on how many mines an individual player can deploy?

This falls right in with deploying Galaxies/Sunderers as part of forward bases, a player should not be forced to not pull more vehicles after deploying them, nor should mines instantly disappear either, otherwise it's too restrictive. I can damn well tell you I won't be deploying mines very often if they instantly poof.

A player should not be punished for switching roles/classes in the middle of a battle to respond to changing combat conditions.