From time to time has 2 different meanings across 2 categories:
sporadically and infrequently
"he was arrogant and occasionally callous"
"open areas are only occasionally interrupted by clumps of trees"
"they visit New York on occasion"
"now and again she would take her favorite book from the shelf and read to us"
"as we drove along, the beautiful scenery now and then attracted his attention"
Occasionally; sometimes; once in a while.