Below is a passage taken from this article
I don rubber gloves, bravely grab my pickup stick and swallow the remainder of my coffee. It’s not even midnight yet. I remember the advice of my former roommate who — once and again — occupied the same stool I stood up from.
Does the last sentence I italicized means his former roommate used to work at the shop before, and has again came back to work there for the second time?
I had never heard the expression "once and again" before!
According to Merriam Webster, it has the following definitions:
once and once more
two or more times
now and again, from time to time, occasionally, sometimes
In the context, it seems to have the third definition - which, until now, I knew as "now and again" (which makes just as little literal sense, when you think about it!) or "once in a while".
It could be the first definition - s/he had had the job once before, and now has it again - but this requires two tenses, meaning the sentence would have to be restructured:
"who had once occupied, and once more occupied..." (or "who had once, and once more, occupied...")
Similarly, "two or more times" requires "had occupied:
"who had occupied - two or more times - ..."
This dictionary has only one definition for "once and again":
repeatedly, as in "He has been told once and again not to slam the door."
This just doesn't seem right in the example sentence, as we don't talk about someone "repeatedly" going to work or having a particular job - they just have the job, or work there "once in a while".
Once and again is pretty old-fashioned to me. I would use "now and then", "from time to time", and "time and time again" for various shades of meaning. "Now and then" means occasionally; there's a sense of irregularity about it. "From time to time" is still not often, but there's a sense of more regular occurrence than now and then has. "Time and time again" means quite often, sometimes too often, as in being told time and time again not to slam the door. For the OP's sentence, I would most likely use from time to time.
