Hmm...not to be critical, but I was under the impression a 'single entry' implied a single forum post. Part of the challenge for myself was distilling what could have filled several pages into an descriptive text that didn't occupy more than that. However, the part about 'write as little or as much as you want' does sound like you could fill twenty pages of the Forums and label it a 'single entry'.
The important part is the sharing of backstories, though, and I think you did that
Actually, my entry was condensed. There is a lot more to many of these characters, and two officers were actually omitted. Hard to consolidate years of work and still get a feel for the characters involved for me.
The topic question is rather broad since my series is in full swing with about 12 different characters just on one ship alone. I try to do one post at a time, but sometimes it takes more than that when there's something I want to convey.