This is very similar to the extraction method I use. One difference is that I do two quick washes.
Once I pour the alcohol into the bud, the alcohol goes back Into the freezer. The extraction container is also chilled before the extraction. By working quickly and maintaining low temps, my second wash is also amber, meaning I get a second wash with very little chlorophyll.
Ive dried bud that's been washed with Everclear once, twice, and three times on numerous occasions over the past 4-5 years. While there isn't much difference between two and three washes, a significant amount of THC was detected after one wash. I'm convinced that two washes is the sweet spot between high oil yield and excess extraction of chlorophyll, waxes, and other plant matter.
I made oil last night using 2 ounces of lower bud and 20 grams of cured tops. I did two 3 minute washes. I ended up with 11 grams of oil.
What you stated about tops vs lower bud is spot on. I made a 2 oz batch earlier using exclusively lower buds and only yielded 2.2 grams per ounce. Just adding 20 grams of cured tops brought me up to 4 grams/ounce. I like curing those beautiful tops for stash, but they are just too valuable considering the steady increase in demand for oil. It's absolutely insane how many people are suffering these days.
You're confirming a suspicion I've had growing for a while that three washes is an unnecessary use of time, effort, and resources. Two quick washes and find an alternative use for the mash seems to be where I see myself settling.