The edging I tried was called 'faggot and scallop', and my first results were hilarious because I ignored the first line of the pattern: "This edging is worked sideways". Even though there was a photo right there in the book, I managed not to notice that the stitches went sideways. I did wonder why the picture looked like it was a few repeats and yet the pattern appeared to only give one. I also wondered why it wasn't presented in a more user-friendly way - as, you know, 'a 9-stitch repeat with 4 edge stitches' instead of just 'cast on 13 stitches'.

So yes, I tried to work the edging the other way around - imagining I would ultimately knit the whole thing in the round. I calculated how many stitches appeared to be part of the repeat. I ploughed ahead, making things unnecessarily complicated. As I cast off a puckery mess, I began to wonder if it would really block out to look anything like the picture. Then it finally clicked - the edging is knit sideways. And that would certainly make it easier to get it the right length to go around whatever you are trying to edge - you just keep going until there is enough.

I picked this one to try first because seemed to meet my requirements of not being overly 'lacy' for the t-shirt edging. I think it is because it is kind of angular. Yet when I held it up to the t-shirt, all that mesh just looked wrong. I could see that it could be kind of interesting sewn a little above the edge, on the right side, so that some of the fabric showed through. But it was too 'lacy' looking overall - both because of the see-through mesh and also the larger scallops. The one I settled on the next day was more subtly scalloped and less holey.
I think it's interesting that I have certain criteria in my head for something like this, but when I actually try it out, they end up shifting significantly. It's not the first time this has happened. I have to be willing to question some of the things I think I'm sure about.