off and on

off and on
on and off & off and on
occasionally; erratically; now and again. •

I feel better off and on, but I'm not well yet.

He only came to class on and off.

* * *
also[on and off] {adv.} Not regularly; occasionally; sometimes. * /Joan wrote to a pen pal in England off and on for several years./ * /It rained off and on all day./ - Sometimes used with hyphens like an adjective. * /A worn-out cord may make a hearing aid work in an off-and-on way./ Compare: BY FITS AND STARTS, FROM TIME TO TIME, NOW AND THEN.

Dictionary of American idioms. 2013.