5.5 inches in two segments is max safe limit and even that is very very tough to do (8cm femurs and 6cm tibia) a lot of people can’t physically or mentally achieve that only some
And to add to this, it's generally for people who were already moderate height to begin with or have the leg length to do so. At 5'6" if ur looking at 6~6'2" you have other problems, sorry to disappoint. There's people at 5'9" with short legs who are satisfied at 5'11" because they look proportionate, or 6'3" happy with 5'6" cause they're pretty mentally healthy.
I'm with u for having a unhealthy mental but I know I wouldn't bother thinking about spending my life saving up money just to splurge it on my legs, and then quit the jobs, go through surgery and finish with no positive end result except for some bonus height that makes me tall and not average or slightly taller than average vs slightly shorter than average.