First trick? there are fads in interviews. When I go through a round of interviews? there is always a lot of overlap between one company and another in the same location at the same time.
Second trick? Most places are cool with interviewing you once a year. In my experience? the second interview at the same company a year later is more different than a second interview at a different company a week later, but still, there's a lot of overlap, and most companies are actually pretty okay with you trying again every year, if you are close (and if you aren't close, you usually won't make it past the phone screen)
When I was a contractor, I lumped all my interviews into around the same time of the year, and I interviewed with all the top tier companies, a few of the second tier companies, and occasionally one of the not so second tier companies. (The latter mostly because those are usually the easiest interviews and they usually got back to you fastest, so it was a good ego boost, and a good way to negotiate my yearly raise as a contractor) I didn't have a spreadsheet or anything, but often the recruiters at my targets would hit me up when that year was up. Or I'd start wondering how long it had been since my last raise.
But, point being, when you interview? always remember the questions you got wrong. I put any memorization/trivia into flashcards the night after, and I practice the flashcards year round. Keep the old ones; you won't get those questions as often, but you still get 'em. And they are usually interesting bits of trivia that can come in handy in other cases where you want to look smart.
Go through any algorithms you didn't get with a friend to make sure it is what you think it is, and then with a book or online resource. Note, it's totally okay to ask the interviewer what algorithm it was supposed to be if you get it wrong; I mean, you still got it wrong, but if anything, it shows enthusiasm and willingness to learn.
Also, interview in clusters. At least in silicon valley, the fads change pretty quickly, so the more interviews you can do in a row, the better.
Being a senior engineer is not normally about raw coding skill -- it's about knowing how to design a complex system, knowing what can go wrong, being able to collaborate effectively with others, and so on. The specific language used is not normally going to make a big difference in those areas, although candidates who need to pick up a new language are going to take longer to ramp up.
My personal impression is that it was pretty clear to all involved what they'd need to pay me, and they slotted me in at a tech level that made that ask reasonable.
(but then, I think that ask really was reasonable for my skill level and the current market, if anything in this market can be seen as reasonable, so I guess in the end, that means the same thing as slotting in my level based on my skill level. But google and the contracting house both had a lot of information about what I was willing to accept, and about what other companies were willing to offer me. I have a very open negotiating style.)
My other impression is that I totally would have had that senior title at a smaller company, but I wouldn't have gotten paid any more, so again, the money seems to be the honest signal.
EDIT: I completely screwed that up. L4–L6 map to SDE1–SDE3.
Sometime after I left there was a big push to get more and more L5s on board, at the point than in some teams L4s were effectively sidelined (and found themselves with little no ability to advance to L5 depending to org politics, in some "high growth" ops teams they made for convenient beasts of burden...)
From the outside (I've never worked at any of FAANG, I don't even work in the US) it seems to me that they are the most likely of those companies to actually hire seniors as seniors, simply because they appear to have made hiring preferably seniors (in terms of experience, not in terms of age) a strategy, while the others all seem to have made hiring huge numbers of inexperienced juniors their strategy.
