Quoting: Schuyler
That's basically what I'm trying to reiterate NHL sizes are wildly inaccurate across the board and only really get changed if requested but it is very rare to grow past the age of 18 as you probably know
During their draft year, height/weights are collected often from central scouting. Early on, it’s often the only interaction that is had with players. It’s usually done at any sort of cattle call (tournaments, prospect games, etc). But some players don’t measure (some play in a league without any prospect games, or don’t play in tournaments…or some just don’t want to measure). That info is then shared with all 32 teams. The last crack central scouting has is at the draft combine…which then becomes the last ‘official’ measurement. After that, teams list whatever they want to list.
For instance, Jack Hughes was listed at 5’11” 170 lbs…but he never measured with central scouts…and was probably closer to 5’10” 150 lbs in his rookie year (if even that). He has added a good 25 lbs since. And grown an inch or two.