Here's a pretty good chart (with visuals) for different sizes.
https://suzyquilts.com/quilt-sizes-chart/
Me? My brain and my preferred project size is queen sized. I seem to be incapable of doing anything much smaller than 36" on it's shortest side and it is with a lot of difficulty that I can get a top to fit on a single width of fabric. Last year I did make two preemie tops just to prove I could. So typically for a "small" project I end up around 4 x 5'+. I want them big enough to wrap around shoulders, arm tip to arm tip is around 6'+ on an average person.
In these days of rulers and such, some of the old school things I do get giggles from people. But almost all of us have a good 1 yard measurement from the tip of your nose to somewhere on your hand, maybe the farthest pointy finger maybe less. Grab a tape measure and practice it and find where your sweet spot is. Comes in handy when confronted by a big piece of fabric at the thrift store... Also good to know that most of those big basic square floor tiles in stores are 12".