It is typically slow after Christmas till New Years eve. January is pretty slow because people know that the credit card bills will be coming in February. Then the credit card bills come in February. Then March is catch up month. April is tax month and finally May comes and things go back to normal.
Last year I was really surprised that neither company offered promotions. Of course, when the time came, I had a lot of $10 + $20 flat surge rides on Uber, and a few on Lyft. Most of those were really short rides.