Yes. I'm claiming that 4x 2sec is less then 1x 10sec.
Hate to jump into this little flame war, since it is going so well, but Katitof you ignore that pios do not get to build each plot instantly. They have to walk between the posts. So the total time is longer and dependent on how many grids you make.
I still don't think these should be nerfed as they are extremely vulnerable to things other than minesweepers. Use indirect fire weapons or drive one vehicle over them, done. If you can't be bothered simply walk around them. No other mine let's you know it is there. If you want to nerf the mines in some way, the signs must go.