No VS19 on Tuesdays?

I flew VS19 to SFO today (Monday) and while I was chatting to the crew they mentioned they had a 3 day layover - coming back on Thursday night - because there is no VS19 tomorrow. I was intrigued so I had a quick look at VS online bookings and there is none on 24th or 31st Jan. I always thought this was a daily service. In fact I just checked on the schedule calendar and it was.

Does anyone know why they have changed it? I wonder if it was just too empty every week.

In contrast VS19 today was packed with every seat +1 taken.

Thanks

Martin

Possibly adhoc cancellations as January is usually pretty quiet.