If I understand your post correctly, 3 or 4 Vermont 9-months' regiment gave it all they had at Gettysburg and the state had no further contributions to the war.

One thing you obviously don't understand is that Vermont did not create a new regiment every time one of them became depleted like most other states did. The 1st regiment was a 3-months unit, like many others at the very beginning of the war. The 12th-13th-14th-15th-16th regiments were 9-months men called up for a specific purpose (a 'surge' if you will) that ended with Gettysburg. But the remaining regiments, 2nd, 3rd, 4th, 5th, 6th, 7th, 8th, 9th, 10th, and 11th were regularly refilled with recruits and were at least battalion size or greater throughout most of the war, while regiments from other states were barely able to maintain a basic organization.

The biggest contributions Vermonters made came after Gettysburg, at the Wilderness, Spotsylvania, Cold Harbor, Petersburg, etc. And, if you read a little bit father afield, you'll find out a Vermont regiment was the first to enter Richmond

"Once bitten, twice shy" is not something you can accuse Vermont of, during the Civli War; maybe a bit of Yankee thriftiness though, in rebuilding regiments, thereby saving the bucks by not having to have dozens of new flags every couple months.