Adverbs of Time and Place - Adverbs of Low Frequency

not at any point in time

at any point in time

in a manner that almost does not occur or happen

for one single time

for a single instance

for two instances

on a very infrequent basis

used to refer to something that happens rarely or infrequently

on very rare occasions

at irregular and unpredictable intervals of time

in a way that is rare or not customary

not on a regular basis

on irregular but not rare occasions

on occasions that are not regular or frequent

at moments that are not constant or regular

at infrequent intervals

now and then or from time to time