Something like that is definately going to be suboptimal. First of all, you can't just assume that your technique will remain on point without actually practicing the lift, it will deteriorate. Secondly, how much weight you can move is not just dependend on the size and strength of the muscles involved, but also on how efficiently you can realize that strength through neural pathways. If you don't teach your body to perform the lift, even if your technique magically remained sharp, your ability to move heavy loads will suffer.
I'm sure others can explain all this better and in more detail.
As far a as the deadlift is concerned, I can see two major factors why training in this fashion might make more sense than with the squat:
1) Deadlifting is more taxing, making it harder to maintain higher frequencies.
2) At least conventional deadlifting is a bit less technical than squatting, so frequent practice isn't as important.
Personally, I'm a bit doubtfull about improving the deadlift without deadlifting, but it has worked for some. For squats, I think the idea is terrible.