off and on

off and on также on and off

Не равномерно, не регулярно; от случая к случаю; иногда;

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.

Ср.: BY FITS AND STARTS, FROM TIME TO TIME, NOW AND THEN.