I've made this profile specifically after seeing this post. I feel that when situations come up like this in a game's development you need to take a look at the objectives taking place.
When a gaming community has developed into the belief that there is only one, precise way to do things correctly-- specifically the mining-- there is a problem.
This isn't a problem of new players or veterans but that there is only one reasonable way to do things effectively.
The problem is that mining is no longer a game mechanic, but a procedure taken upon by players.
And I'm sure the noobs want to find out what they are doing wrong just about as much as the vets want to yell at them for it.
If all your mines are getting used the same way every game there needs to be a different way of preventing stealth assaults: because obviously without this stringent mining strategy players feel the game is unenjoyable without it.
On a side note mines are intended for the field that why we have both Anti-Tank and Proxi Mines, and in other games its pretty damn fun to f*ck with the tanks rolling into the field.
I'm going to leave the suggestion of door-guards up in the air because it needs a bit of balancing, but mines should get a timer, and I think 180 seconds is a perfect setting for this. Perhaps you could make it adjustable if some would prefer. But when and if mines are going to be used in the field and have an entity limit there needs to be something regulating that players have the chance to use a game mechanic as part of their strategy. (and we don't have 30 mines in god-knows-where).
Thanks for hearing me out.
TL:DR- Put a 3 minute life on mines and Axesor's 3-laser doorways is golden.