I understand the importance and logic behind using a test base when adding other compounds. If you go to the TRT forum you will see that those guys keep their levels in the normal range and they almost all use an AI.
An AI is not the same as a DA (e.g. caber), and is very useful when using a 19nor. Using an AI to help keep e2 within range will make using a DA redundant. This is because for prolactin/progestin to be an issue e2 needs to be elevated. Having elevated e2 is probably the most unhealthy event that can happen on cycle.
Half lives are not as straight forward as one would think, there are many facets involved. Some components which affect hormone half life include BMI, metabolism, amount of esterase and most importantly injection site. A compound with the acetate ester can have a half life of anywhere from 1-3 days.
Steroid calculators are not very useful. This is because they do not show a true reflection of what is happening inside your body pharmacokinetically. Steroid calculators only use one equation, half life. Have a look at the attachment to see some of the formulas used in determining the pharmakinetics of a compound. That formula sheet doesn't even include taylor or maclaurin series.
Useful Pharmacokinetic Equations
People have been using sust 250 on cycle, while injecting twice a week since the 80's, with the same results as those who pin EOD. Comparing those two cycles on a steroid plot is frighting, but not a true reflection of what is really happening internally. If you want to pin ED then that is fine, but not necessary for a safe successful cycle.