I don't think DLM changes once a week - going through all the reported DLM changes in this thread no one has had weekly DLM changes. Monthly changes seem to be the norm when DLM is not in it's rapid change state making changes every 2 days.
I barely saw any changes in the initial 10 day period other than it dropping me to DLM3.
My recent changes though were fairly quick, with each one happening ~2-3 days apart I think (to get from DLM6 to DLM1)
Maybe once it decides you're due an upgrade (and maybe the error rate is low enough) it does them quite quick?
Also interesting that a few people have reported no changes at all in the 30 days or say after the initial 10 day DLM.. and then changes. Maybe it chooses a level during the initial 10 day period, then sticks with it for a good month to gather data, then when it has enough data makes more changes. Though I know other people have had other experiences!