Isn't it pointless to mirror maps that are already mirrored?
You know like well and sawmill
In some cases. Well is pretty much mirrored down the middle making it pretty much pointless to mirror. Sawmill works as either side is a rotated copy of the other and not actually mirrored.
There are exceptions though, Nucleus for example.
Nucleus uses reflective symmetry, so when the map is flipped either horizontally or vertically the result is simply switching the teams in terms of their navigation. So if you are a Red player who usually exits spawn to the left, you would now go right just as you would if playing as Blu in the original map. It would still mess with you if you only usually play for one team, but it would be a much more subtle 'mindfuck'. Maybe it would be even more unsettling having the feeling that something isn't right but not being sure what.
Pipleline is another example..
Hydro, being asymmetrical would work well..
Im still leaning towards Badlands being the 3rd map for series 2 though..