Configurable ADC update rate

Shortly, simple solutions like the above are unsafe and can cause Timer Too Close.
Long, it is possible to do it slightly differently:

And maybe there, but it is autoclosed: Discussion/Proposal: small heater control improvements


But, in the end, graph and temperature fluctuation is not a problem by itself - fluctuations happen anyway during printing. The issue is when they cause real differences in the output model and it can be proved.