Apologies for raising a possible inappropriate deviation from a system. Also this relates to the GiB 2/1 system but more broadly to No trump target point ranges for game.
Lets start with an assumption. You need 25 points for a NT trump game - just an initial assumption (not a hard and fast rule)
The 2NT ranges I often read about online are 20-22 points with 4-5 points response giving enough for game
The 2NT range in GiB 2/1 is 20-21 points with anything from 5-10 points leading to a 3NT response
I have found these to be far too conservative and occasionally (not often

If you run Sims on 5-10 point range surely 20-21 is far too conservative. I appreciate with only 4 points opposite you may be struggling
Would be interested in any discussion. Similar considerations for 1NT I guess
I should add that I am thinking of things like match points where I believe there is a 50% target for game bids. Then of course that percentage depends on your opponents does it not
etc
P
PS I hate to be seen as causing trouble for Novices and Beginners but when I read pages on the Internet about such matters that say "***** is far too complicated for beginners and we aren't going to discuss it" a bit annoying. But I'm not a teacher so don't patronise my students in that way. I remember annoying teachers at primary school with questions outside their skill level