Is there a good "starting dose" ratio for test/ai tren /pa

For example, if your dosing 500mg of test per week then a good AI start point is .25 eod of dex, what if the test is 250mg per week, would the dex dose be .125 eod? what if test was 750mg per week, would you up the dex to match as a good starting dose?

What about PA, wouldn't you also want a higher PA dose with a higher tren dose?