I don't think that would be fast enough for me. I'd first have to feel around with my pinky, then make sure I really found the Ctrl key, then move my other fingers. Doing this while under heavy fire, when every split second counts, does not sound comfortable to me. When my fingers lose orientation, then I simply lay them flat on the keys, which immediately tells me where the F key is due to the nub. I then move my index finger to the nub and am back in action.

The speed of either operation depends highly on training, of course, and there are differences between individuals, but I know from experience that I wouldn't be able to perform the operation that you are describing as fast as the one that I'm using.

Yes, but that's still a limited selection of keys. One reason why I settled on FDCG (after experimenting systematically with every alternative imaginable) was that it gave my pinky easy access to 4 keys, extended access to 6 more keys, and far access to 6 more keys (including the Esc key, which many games don't allow to remap, so it was important to keep that key in reach). The pinky is the only finger that is not involved in movement (apart from the thumb, but the thumb has extremely limited access to keys), so it's very useful to give it access to many keys, it makes it easier to perform time-critical actions while moving.

(Side note: The three access categories may need further explanation, as they emerged from my experimenting and nobody else knows how I define them. "Easy Access" means keys that can be used without impacting the mobility of the other fingers at all. "Extended access" means keys that I can't use without reducing the mobility of at least one other finger, and "Far access" means keys that I can only use without using any other fingers, but that I can still find blindly and return to my starting position afterwards. I found those categories helpful while doing my analyses.)

I think it depends on the game and the gamer, as said above. Parameters on part of the gamer could be the difference in length between the three longest fingers (which varies a lot among people, especially the length of the index finger), the angle at which the gamer puts his hand to the keyboard, and personal preferences of which hand posture feels more comfortable. I know that my middle finger feels "spread out" when using WASD for an extended amount of time, and having it on the home row allows me to use it extensively for movement without having to stretch it, which is much less tiresome in long sessions.

Parameters on part of the game are a) how many other keys are used and need to be in reach, and b) how important the "down/backwards" move is. While putting the index finger on the homerow makes pressing "up/forward" more convenient, it makes it more difficult to press "down/backwards". For some games that doesn't matter much since the "down" key is rarely used. For others (e.g. shmups, or racing games that require precise braking) it can become an issue. But I usually remap the "down" function to the space bar for those games - this means that all four directions can be accessed quickly without having to move any fingers, and it also works well with giving the pinky access to lots of keys, so that the four other fingers can rest on the movement keys whenever possible.

Anyway. I _did_ warn you that I am quite mad with regard to input efficiency. ;)