Optimal vaccum in Hg for best gains

I’d like to know about most of you who have gained permanent inches in both girth and/or length, what was the vacuum that you found most effective ? I have to say that I’ve recently started pumping (I did in the past for one year—that was years ago). I bought a LADIST deluxe brass pump with gauge, and so far have used no more than 5 Hg in my sessions, and I have to report gaining 1/4 in girth so far. I’ve been at it for two weeks, and also do some ulis, and squeezes here and there. I’d like to get your feedbacks on what you assess provides the best gains in terms of Hg ?

P.S. I want to emphasize that above where I mention permanent gains, I mean those that stay after a while after you have for instance discontinued using the pump. Like in bodybuilding, if one stops lifting weights, then he loses some of the gains, but usually retain some of those too.

Thanks