I find 1 week ideal without the overhead.
Remove unnecessary demos or retros. You need the feedback cycle but often 1-3 months is fine, and 2 weeks is only useful for a beginner team.
You do need planning, context, and meetings to discuss the context. We moved these to two days a week where anyone is free to interrupt anyone else and call for a call right now. Nobody expects to be in flow on these days. But as we got better at teamwork, we only needed 0 or 1 days.
We do have 1 week sprints but it's about 90 minutes of sprint related meetings/week on average and that includes stand ups, retros and demos.
Work estimation into the schedule. They're called spikes. Time box them. No commitment is made without the confidence of the spikes. If you don't have confidence by the end of the spike, then something is wrong - the requirements is unclear, code is too opaque, you don't have the data, someone isn't cooperating, etc. These are all very valid outcomes of a spike. Maybe you need to call someone. Maybe you need to refactor.