...plasma is the only reliable way to deal with mid to late game enemies like the upgraded sectiods, mutons, turrets and ethereals aside from packing enough cheese to be declared legally French. Leaders don't grow on trees, so if you are at the stage where you have a limited number of captured aliens, "leaders always first" won't always be the fastest option
I have no idea what you're talking about. Plasma is endgame weapon, gated behind advanced lab (and IIRC delta radiation, of all things), and these are endgame-ish enemies. You don't need plasma to steamroll through midgame, neither it's required for dealing with mutons / turrets. Upgraded sectoids are semi-optional enemies altogether.
And if "leaders don't grow on trees" for you, then you need to focus on them being so. Pretty easy to minmax on capturing leaders - most races have colored leaders, you can filter medium UFOs, and so on.
You do you, but 25% is greater than 20%, this is math not XCom shooting odds
First, that's just asspull number, not "math". Second, it's not 25% per leader, that's 25% per that one tech, and it becomes 20% again, because junk / good ratio decreases as you've removed good tech from the pool. This means you pretty much need to exhaust research pool to get something reliably done.
Third. Where does this "odds increase" even come from? Most leader's tech are leader's only, meaning you get them from leaders and can't mutate junk/good ratio by researching other aliens. And by leaders-only I mean, they have 17 early techs (all junk besides medkit). Then there are ~9 techs, gated behind alien vocab, that give you adv lab and other good stuff. Getting vocab is the first step. Out of 17, 8 are medic's tech, 6 are engi's techs (5 of 6 needed for vocab) and 4 are leader's only ships.
Now, 8 medic-shared tech are the problem. There's about 45 medic techs, of which ~40 are junk autopsies. So manipulating leader's tech by researching medics is negliglible.
So effectively 12 of 17 leader's tech are leader's-only. Maybe 10, if you're lucky with medics.
You may "optimize" 5 leftover leader-shared vocab techs by researching 10-20 engineers and 0-10 navigators (to reduce engi's ships). Which means you'll also have 10-20 leaders, depending on your battlescape success.
After you unlock vocab, you may start getting lasers or progress towards adv lab. Which is best done through leaders, as engis have too much extra junk and autopsies mixed in. And at this point you'd have 10-20 leaders, enough to exhaust their entire pool. So you might have started working on them anyway beforehand, and unlocking vocab faster in game time.
And if you focus on just leaders from the get-go, you'll get to adv lab in minimal lab time. Not necessarily game/RL time, but this depends on how you pick and proceed through your encounters. For some alien races are hard to capture, so blanket capture is not an option. Thus you focus on capturing none of them, or some of them (guess who).
tldr: you need to exhaust leader's research pool to get to good stuff, which means getting to late game after 30 or so UFOs, a few steps from the end.
There's no lottery involved because to exhaust leader's research pool you'd need to research almost everything anyway. And you'd get core techs to combat aliens way before that.
That's pretty reasonable midgame progress model. You don't progress due to luck, but due to quantity, and each engi/leader counts.
Also, this seems unpopular, but I'd say midgame is pretty fun actually. It's just differently structured than early game, and some weird slog missions appear, like, second half of cyberweb (3-4 almost 1-1 sam-y missions with 100 enemies), zombie arc (3-4 almost 1-1 sam-y missions with 100 enemies), etc. Early game is full of short, fun, tech-wise profitable missions. Likewise some medium-and-below UFOs can be short and sweet, and you can choose if you want to battle larger ones.
