How long should an iteration be?
The iteration should be short enough so that customers can wait until the end of an iteration to introduce new changes, and it should be long enough to allow a system to stabilize. An iteration that’s too short will not result in a stable cadence, as the team will never have the opportunity to deliver finished work.
If there’s a big pile of work at the end of the iteration, then the iteration is probably too long. Some people might argue that the cycle might be too short because the amount of overhead imposed by the process seems too significant. Focussing at the actual work at the end of the iteration shows that this work is not related to the process at all. Shortening the cycle will even out the workload.
So don’t increase the length of your iterations in this case, but rather shorten it.