Yes, they do decrease between injections. Typically TRT uses Testosterone Cypionate as it's Testosterone mainstay. That has a "half-life" of 8 days, where at that point about half of that is gone from your system, then another half of that again the same amount of time later. Over 4-6 injections this builds up from each to help maintain a stable hormone level but the day of/the day after an injection is still going to be the highest spike.For Testosterone, you just want the average between injections to feel really good to you & adjust based on how you feel. For Estrogen, because aromatase occurs based on Testosterone level spikes rather than their average, you'll see a significant rise in it right after injections but typically below a certain point more does not continue to convert.That Estradiol is an elevated value, but how it makes you feel matters a fair bit as well. If you're not having any high Estrogen symptoms & like your dose/regimen, this is probably fine. If you are experiencing symptoms, then lowering your overall dose, spreading out your dose via more injections/lower volumes, or taking an AI may help you.