Email and password changes are valid prompts to investigate or keep an eye on an account, as are 2FA changes, as they show that a change has been made to an account.
How would you possibly know this if you've never actually found a single alt account? You take grand liberties assuming how things work with no actual experience to back it up.
To say I do not know how to spot them just because I haven't (yet) posted about them or use my (useless) tag for my observations is a poor assumption.
Anyone can say they are good at anything, but the proof is in the pudding. So far you've offered no actual proof of anything. So I think my assumption is justified for now.
I've already got proof of a merit source farming accounts with hard evidence that I'm posting soon, which ties together a ring of 10+ accounts that have shared thousands, maybe tens of thousands of merit with each other and as a result farmed tens of accounts unfairly...
Like with your claims about gathering evidence that Medusah is an alt account (for which you already left them a neutral tag), I doubt you'll ever actually post it, but I'm looking forward to being proven wrong.