"Once in a while" is the same as saying "every now and then" or "from time to time".
1. I don't get on Facebook every day… just once in a while.
2. These days, do you see your best friend(s) once in a while because you are so busy living life?
3. From time to time I transfer or upload the video clips stored on my phone to the internet so that they are not lost if I lose my phone or it gets stolen. It's a good idea to back up any type of information periodically, just to be on the safe side.
4. Standup paddle surf is the type of hobby that gets boring (for me) if you practice it every week… So I only go every now and then.
5. What activities do you only do once in a while because they are kind of expensive? It's not every weekend that I travel out of the city.
6. From time to time I clean my air-conditioning units… However, I really should clean them more frequently. What activities, responsibilities or tasks do you think you should do more often?
7. Every once in a while there are strikes throughout Brazil. Once in a while it's the post office or the schools… But most often it's the banks.