There's a thing called the "financial year" which usually runs from the beginning of April through to the end of the following March. So yes, whenever you see stats for toku seasons, it doesn't really match up.
What people usually quote is the financial year that corresponds with most of that show's air time. But even that can be flawed, as most of a show's toy sales happen in the first three months of it being on the air. In the case of Sentai, two of those months will be at the end of one financial year and the last will be at the beginning of the next financial year.
(Sentai has also taken a knock because they used to receive some money from the Power Rangers brand which contributed to it's figures, but since Hasbro took over from Bandai as the toy manufacturer - even before they bought the franchise from Saban - those sales haven't counted any more)
With Rider it's a bit easier because the show begins five or six months into a financial year, so the big sales bump isn't getting split up. So we can say that the 2021 year, where Saber will have had most of it's sales, was not as profitable as the 2020 financial year, when Zero-One had most of it's sales. So Saber didn't do as well, but still way better than the other two (and like triple the kind of figures that phase one Heisei used to do).
Of particular note is Ultraman. After years of slowly catching up, it's finally overtaken Sentai in sales figures. But even more interestingly, it still had better sales than Sentai in the parts of the financial year when they weren't broadcasting a new show (and this last year didn't have a movie to fill the gap either). So even without new content, more people were buying Ultraman toys than Sentai toys - even when Kiramager had just started. And Bandai themselves are predicting that this coming year will see them make almost twice as much money from Ultraman as from Sentai.
www.bandainamco.co.jp 
