I have tried to get a rule/correlation between tuner marks and temperature, i.e 1mark/5*F. I could only understand that I have to screw it when temperature rises and viceversa. But a proper confident level requires too many shots. Mine is a EC tunerSet and forget is just like shooting the same load all day, every day...Sometimes it works better than others. Conversely moving the tuner is just like adjusting the load to keep up with tune changes. I'm of the belief that tune changes are inevitable as powder burning is a chemical reaction and all chemical reactions are temperature dependent. If you have a load that stays in tune better than others, you'll simply need to move the tuner less often.
There are lots of ill conceived notions about tuners. I'll say this, as I've said it many times but it's still very true. The most common two mistakes with using a tuner are moving it too far and moving it too often. There are days when I never move the tuner and there are days I move it by a mark or two. Each mark is .001" of an inch. No doubt, enough to affect tune considerably.
Just as weighing each kernel of powder is important to methodically working up your best load, so are even fractions of a mark on the tuner...but being very methodical with either, is the key to success. Grabbing a tuner and twisting randomly is akin to randomly throwing powder charges and seating bullets a full turn of the seater top(or some other random amount). You can luck into something either way but I know no one that thinks either is good nor methodical.--Mike