I like several others always pre-wash to remove any chemicals and that fabric "smell", so no testing the waters there. Then I jump in with both feet, and figure out things as I go. I've never done a test block, just full speed ahead!

Not a pre-washer, I will try a practice block if i’m unsure, I always measure after the first block and adjust if necessary, and make notes in my little book in case I get side tracked, that way I know where to pick up again.

The only fabric I prewash is muslin, no matter where I've bought it. I don't test for possible color running, trust my color catchers for that. Don't make a test block or check the 1/4" seam allowance. So far, (and knock on wood), I've managed to stay out of trouble.

i do not test for fabric bleeding, i do make a test block from my scraps to see what the block will look like.

Pre-washer here! I usually design as I go. Crazy, I know. I'll get an idea, and start, not worrying how the end will be. I have learned to make the first one if many are needed. That way the problems are identified and not repeated on everything.

Once at the start and then randomly, or when something seems off. I possibly do a little extra stitch ripping this way but I'm okay with that.

Yes to all of the above.

I prewash everything, I don't leave anything to chance when it comes to that. I always test the block by auditioning it with other fabrics first, that way I can get the muscle memory going and if I'm going to have problems with the way the pattern suggests, I can take some quick notes and figure out a better way to do it. Once I know I've got all of that done, then I'll stitch up a block with the fabrics I'm going to use and see I need to make any further changes before I commit to the full quilt. I have a really bad problem with getting frustrated quick if I'm having issues while I'm working the quilt and if I get too frustrated, I will abandon the quilt altogether and about 80% of the time, I never go back to it. Taking the few extra steps before I start saves me a lot of time and a lot of money.

I steam and iron my fabric before cutting so the shrinkage will be done and any bleeding will show up on the white ironing mat cover. I wash my quilts after they are made. I don't cut all the block pieces at one time. I cut enough for one block and make it. Several times I have decided not to make the pattern due to the time of making the block.

I pre-wash dark fabrics with color catchers rather than test for bleeding. I've never made a test block. I check unit size, which shows if seam allowance needs adjusting. Most of my 'testing' is in the fabric selection process, with lots of mock-ups and photos; I really rely on my camera for design decisions!

I prewash fabric as I buy it - most goes into the stash for who knows when.

From there - I wing it. Rarely make a test block or anything like that. But then I rarely follow directions. Even if I have pattern, most of the time I come up with my own cutting and sewing plan.