No tolerance. If you work to KNOW where exact 1/4" is on your machine you won't have to worry about it.
And start with pressed starched fabric. Unpressed fabric will grow when you start pressing the seams.
The best way I've found to find that perfect 1/4" on the various machines I've used over the years is start with a pile of 1-1/2 squares and make 9 patches. It is pretty easy to get your 3 patches stitched together to come out a perfect 3-1/2". But when you stitch those 3 strips together into the 9 patch you can quickly find the block is short in one direction.
I probably stitched 2 dozen blocks getting it right on my new Horizon because there are so many setting variables.
Once I had it consistently turning out 3-1/2" square blocks I used a sharpie and wrote those setting on my machine along with which foot.
Do it right and take pride in your hard work and to honor the expense and time that goes into a quilt.
I too have assembled group quilts, it's kinder to just return blocks that aren't right.