One notch (1cm/10mm) can be a lot, just right or not enough - and we've seen all three with my child, but most people can handle more than 1cm changes. My child had two separate adjustments of one cm last year and those were just right or even slightly too much (but slightly too much was better than previous setting and it did smooth out). Because she's been so sensitive, we tend to adjust by one setting. But in the last month she's gone up 4cm and it only slightly helps. Staying hydrated is really important! Note being somewhat/very constipated can also affect draining/pressures. Some people get other blockages at the distal end of the tubing, I'm not personally familiar with those.

If everything else is working, how you generally feel in what positions can guide what adjustments you might need. If lying down help you feel better or you are worse at the end of the day, your setting may need to go up. If being upright helps you feel better, the setting may need to be adjusted down.

A shunt tap can be done to get a ballpark idea of the pressure but it is putting a needle into your system so they don't like to do that. But they already did same for lumbar puncture so they are unlikely to do another for a while. A shuntogram (flow study) might show if things are flowing very slowly but the test is influenced by the skill of the person doing it.