It's a safe bet that any rule regarding English grammar that includes the word "always" is either a) mistaken, or b) so obvious that you probably wouldn't be qu

It's a safe bet that any rule regarding English grammar that includes the word "always" is either a) mistaken, or b) so obvious that you probably wouldn't be questioning it in the first place. Commas began life as indicators of pause, but in modern English they are indicators of clause -- that is, they indicate grammatical structure. The places where we don't normally use pauses to indicate structure in spoken English (but still use commas in written English) are where you're noticing the discrepancy. Specifically, it's a common practice that you should use a comma to separate an adverb (like "too") from the rest of the sentence when it's being used to modify the sentence as a whole. This isn't a struct rule, and some people prefer a style of omitting such commas.