I have a journal. I write whatever is on my mind, whenever it's on my mind. Whether it's once a day or seven times a day doesn't matter. I don't bother to split it up into topics because otherwise I would have seven posts a day, and I have a life outside the Internet (or so I like to convince myself). Yes, this leads to messy posts, or so the overly anal-retentive would say. However, this is the way my mind works, and I can't change that.
I cannot control the updating habits of others. That is up to them and them alone. After all, people keep online journals for different reasons. I started my first one (non-LJ) in 2001 as a way for my friends to peek into parts of my paper journal. Now the online journal has evolved into a writing exercise and a way to communicate with friends I don't see often (or friends I know only online).
I don't get annoyed when other people update what some view as "too often". Why? They have their own reasons--for updating that often and for blogging in general. Sometimes entries are directed at one person, and I'm not one of them. Then I'm free to ignore that part of the entry (or the whole entry, if that is the whole entry). After all, some people do check their friends lists more than once a day, and others do take advantage of that in order to communicate last-minute notices. I've been guilty of this.
Now what about "too little"? No. Once again, everyone has their own journaling philosophy and reasons for blogging in the first place, and I'm not to mess with that. Now if someone hasn't updated in months, I might wonder if that person has died, but no, I don't think there's a limit either way.
Someone remind me to write my Online Journaling Philosophy soon. I've been meaning to do that for months now.