I'd like to offer another suggestion to the OP--
I spent a couple years growing cubes (PE, Cambodians, Golden Teacher, KSS) back in the mid 2000's.
Took a very long break due to job transfers and life circumstances making it impossible to grow or use anything.
I came back to mushrooms just this past year, and was asking the same question as you are: what is the optimum potency available to me-- the "Biggest Bang Per Gram" (BBPG)? I think I have arrived at my solution, and maybe it will help you too.
Within the cubensis section, as others kindly mentioned earlier, you are dealing with any number from hundreds to even thousands of "children" of the mother mushroom in any multispore grow, all working together inside any given monotub grow.
Every mushroom grow can be comprised of different combinations of spore "parents". You're looking at dozens or even hundreds of that patent's "children" in every grow.
With that analogy applied to people, how could you predict the smartest or fastest one of 12 children would be in-vitro? You just couldn't.
Sure, casual agar users (like myself) may well be able to narrow a colony/crowd of mycelial spore combinations down through transfers... but the question of potency is simply not visible on an agar plate-- you can only narrow at that stage by selecting for healthy behavior/uniformity and speed/resilience in colonization.
Just like the smartest child analogy above, you just can't tell how it'll turn out until after they grow up and prove themselves superior.
So here's the answer "I" chose to solve my question-- and perhaps yours, too?
Instead of spinning the potency roulette wheel every cube grow, consider graduating to a stronger type of mushroom altogether!
You have so many seriously potent alternatives to cubes!
While each may have their own spectrum of "Meh, rather weaker" on up to to "[email protected] $#!T strong"... their types "weak" is often at least as strong as the average cubensis is prone to be-- and "strong" might only require a single gram to launch you into a VERY strong trip.
Which types am I talking about?
- Ps. Mexicana (Jalisco, others) (makes stones/sclerotia)
- Ps. Tampanensis (Galindoi, Atl#7) (these are the northern cousins of Mexicana) (makes BIG stones/sclerotia)
- Ps. Hoogshagenii var. Convexa (AKA: Semperviva!)
- Panaeolus (Cyans and Cambo's)
From my (extensive) reading on this topic over the past several months, Pan Cyans can be nearly 4x as strong as cubes by weight-- Pan Cambo's, Tamps, Mex, and Semperviva around ~2x as strong or more as average cubes.
The stones that the Mex/Tamps generate are also worth you time to research, as "truffles" are active just like fruits-- and they form without having to even grow fruit! Hell, you don't even need to take them out of the spawn jar and they'll grown in there!
AND, every type of shroom fruit above has far less fungal matter per alk dose-- they're way less likely to contribute to the stomach gas that makes so many people feel crummy during digestion, making tripping physically uncomfortable.
Anyway-- because of my research, I presently have Tamps (var. Atl#7 and Galindoi) and Semperviva on grain.
I have seen enough reviews to know that these will all provide very solid experiences in smaller, easier to store fruits (with free stones as a bonus for the two Tamps!) with the same number of trips per quart of spawn (and sometimes more) by weight as cubes in less space. They are NOT all that much different from cubes to grow-- I've seen many people here and elsewhere do a stellar job with the same basic skills used on cubes. Just pay attention and go for it-- that's what I'm doing :)

I also have some Panaeolus Cambo prints that I will go after once I get these strains on lock. They are being shown recently as producing some of the highest Biological Efficiency (% mushroom grams per spawn/sub weight) of any active species by a long measure. User Blue Helix measured 170% BE when scaled to the method measuring cubes-- that's a spectacular gram return per unit of spawn and sub.
Pans do seem to need more attention, but I will get them going too-- I have the community to help me along, as do you.
Best wishes--