I have a few questions regarding setting the "optimal" boiler pressure:
1. Do you set it to the lowest setting that allows reasonable frothing, the highest which allows a reasonably short cooling flush or somewhere inbetween?
2. Which is the above will be more thermally stable?
3. Do you set the pressure according to (in ascending pressure order) the lowest it drops, the point where the heating element turn on, the point where the heating element turn off or the highest point it reaches?
4. Setting frothing aside for a second, will a very low (0.8 bar high point) boiler pressure allow making drinks at the higher end of the temperature scale? Will a very high (1.6 high point) boiler pressure allow making drinks at the lower end of the temperature scale?
5. When making modifications, do you try to a specific value or for a specific increment from the previous value? (current pressure is 1.23 so new pressure is 1.3 or current pressure is 1.23 so new pressure is 1.33)
6. When doing pressure modifications, do you do it as a specific time?

Edit: Added 5 and 6.