I always wear 2-3 cm insoles, according to the shoes I wear as with some of them 3cm are too much and my heel is almost outside the shoe, so I prefer 2 cm with them.
I measured myself and I almost gain completely that amount and I walk fine with them. My achilles tendons are very stiff due to at shortening surgery I did and except from aesthetic reasons, some insoles really help to prevent my tendon from extra tension which may lead to microtearings.
I can't wear shoes without even 2cm lifts, even if I could because I still want that extra boost to my height which makes some slight but still noticeable difference.
The best height increase is with my nike air max 720 and 2,5 cm lifts. They give me a solid 5cm added height which is more than enough for me.
Before LL I wore elevator shoes if 6-7,5 cm which always gave me 2-2,5 cm less than their advertised height (due to the pivot and all these). After LL I never used them again. A normal shoe with a 2cm insole give me almost the same added height and I can wear any shoe I want and not some ugly elevators.
I truly believe now that elevetor shoes of 6-7cm are not worth it as you can gain just a little less with 2-3 cm insoles with minimal money and without the bad style most elevator shoes have.