When the timeline is set to 6-weeks, clicking the arrows moves the timeline in 1-week increments.
When the timeline is set to 1-year, clicking the arrows moves the timeline in 1-year increments. This means that if the timeline is zoomed in, there is no way to see the timeline beginning at any month other than January. For example, If I select Year, then zoom in until I see Jan - Apr, clicking the right-arrow takes me to Jan 2022, rather than May 2021. This means I have no way of zooming into those months after Jan, except for switching to 6-week mode.
It would also be nice to have other timeline increments like (at least) 2 years, 5 years.