1 plant per square pruned to 1 stem is what I've been doing for a few years now and wouldn't do it any other way.
I've even allowed 2 stems to grow. I've done this with all my indeterminate tomato plants from cherries to beefsteaks. my beds are 4'x4' w/ a 4' wide trellis 7' high.

Your garden is lovely! That set-up is almost exactly how I envision mine. Thank you very much for the information.

Stevin-I am growing a few indeterminate cherries. Both the black cherry and snow white have come up with multiple stems---maybe I did something wrong when I planted them? Either way, I am wondering if I should let the stems go or trim back to one. I don't want to kill the plants as the stems are clearly all part of one plant. Any help from you or others would be appreciated. Steve

I second going down to only one vine for most indeterminate varieties, but I have found it is very easy to manage two vines when it comes to cherry varieties. I allow a sucker to grow at the first flower tier on my plants then keep them to these two vines from there on out. It increases your production pretty considerably and they do not end up crowding each other. I keep my larger varieties to only one per stake. You can see how i have it going this year. I put these in the garden around April. They are all spaced one per square foot.

If I only had a single box, I'd prune to a single vine. But, I have multiple boxes and really, really love cherry tomatoes. :) I prune regular tomatoes to a single vine and stake it, but I let cherry tomatoes go crazy. I plant them in a corner square in a tall tomato cage and individually stake the larger stems as they grow. I kinda love a big tomato tree! ;)