I find that Gem's take off a lot more stubble with the atg pass than d/e razors.So for me a third pass is not required.
That is my normal SE shave also. Turns out a DFS everytime. Specially with my favorite 1910 model Gem. Fuzzy
To be clear. A skilled shaver using the right pass combo can get a very nice two-pass shave. It will likely not be BBS, but will suffice as a good shave. Personally I like to go for as smoothy smooth as I can get w/out irritation hence the extra passes. And I've never shaved a Gem so can't comment on how they compare.
Not necessarily I can start with an ATG pass, it is not as effective as and ATG pass that followed a WTG pass but I can lead off with it. I will do this on some days when I am in a hurry, I will do 2 ATG passes (from opposite directions) and call it good with minimal touch up.