Yup, no magic number. Look around in here, e.g. raptor is at 140kg squat / 80kg PC. Or me , 110kg squat / 60kg PC. And then you have adistardkfjgdhskdfsfgj, 60kg squat / 65kg PC.
No ratio knows your individual unique body metrics, levers, specific strengths etc.
Also, (i think) LBSS does not mean he wasted the time while he should have stayed e.g. at 1.25*BW. He ( probably ) meant that it wasn't worth it when it deviated too much from linear progress.
I guess you can resemble squat gains with a logarithmic growth curve graph :
Horizonal axis is time, vertical axis is squat gains, forget the scale numbers.
So, from the beginning of the curve till dot #1, it is the newbie gains, 4 squat units gain at 1 time unit.
From dot#1 to dot#3 it is more or less linear, 2 squat units gain at 3 time units.
Above that, it becomes too hard, 1 squat unit gain now needs 4 time units.
So is it worth it to, say, spend 5 months to get your squat from 1,9 to 2 ? Jump-wise, not. Posthumous-fame wise, hell yeah!