I only check the ones that I have noticed visitors are coming from. I have a large portfolio of sites so it would take me all day to check the keywords. I do not think it is that necessary to do it everyday anyway due to small incremental increases that you might see. I am looking for large jumps and usually that is marked by an increase in traffic, at least with my site anyway!
Honestly I hardly ever do for one forum as it's in such a large community it's never close to the top but on my theme forum I'm usually on top with my key words.
I check every few days. I really like this McDar Keyword Analysis tool. It's simple and quick and also displays allinanchor ranking and google/yahoo backlinks. Here's the link: McDar
I use market samurais rank tracker which makes the tracking really easy. Since its just a push of a button I check them almost everyday!
I do it daily when I make new website to be sure that 's I am going right ,,,, but after my site get raked well ... I do it every some days and may be every week. But ,.,, I checked every day the number of my unique visitors ,,, If I found something different from normal then I do check my keywords ranks.
I check daily, but unfortunately it doesn't change daily. I just like to hope that it will have changed