Is there a 1 syllable word for often?

Answer 1

Yes, the word 'oft', but it is an archaic word or only used in 'literary' works.

e.g.

"Oft expectation fails, and most oft there

Where most it promises; and oft it hits

Where hope is coldest, and despair most fits."

[Shakespeare: All's Well That Ends Well, Scene II, Act I. Words spoken by Helena.]