^ If you’re applying to schools that don’t admit by major, and aren’t dead-set on one particular path, that advice IMHO is less relevant. My rec-picking advice, in the absence of college requirements to the contrary, would be teachers 1) who know you well, ideally recently and both in and out of class, 2) who teach a core (math/science/English/history-by-which-I-mean-actual-history-not-social-science/foreign language) class, and ideally taught you in that core class, 3) who can speak to your strengths.
My kid, who is sort of undecided social sciences and (due to indecision) isn’t considering any schools that admit by major, plans to ask a science teacher and a foreign language teacher, because she has good relationships with both of them. It’s possible that she won’t even take the offered AP most related to the major she’s currently thinking of indicating; even if she did, she’ll be asking for recs before that teacher has even seen her name on the class lists.
If it were my kid asking, I absolutely would not ask a 10th grade teacher just to get a math letter in. Schools understand that sometimes teachers reach capacity (or are just terrible people with no business writing rec letters, or any of a million situations in between).