I think we may have different definitions of squaring up. To me, it means checking the size of the block (frequently if necessary) as it is being built. If it doesn't measure as expected, I figure out what is going wrong and fix that problem. As a result, I very seldom need to shave any fabric from a block (except when I've purposely made the patch larger, so I can cut it down to its proper size after sewing, as with HST's). I think it's much more productive to strive for accuracy in cutting, sewing, and pressing. Then "squaring up" just means verifying that the block is the right size and shape.