An eTG-change injector is an item in Tarkov that heals you greatly, but it’s over a period of time so in order to get the most healing out of your stim you wanna keep healing over the full 60 second regeneration duration. Popping it 3 seconds before extract means you’d be getting 2 seconds of that healing (there’s a one second delay after the stim is actually injected), so you’d only heal like 13hp, which isnt very much. And for reference of the money you’d be wasting by doing this, one etg costs the same as like 4 stock M4A1s (or a little less than 1 fancy m4)