You can place your cursor in the band with the "tabs" at the top and, if you have a trackpad, swipe left or right with two fingers. That is much faster than clicking the arrows.
You can also use this Jump to Sheet Automator Service (Dropbox download). After you hit a keyboard shortcut (I use shift-command-j) it will give you a clickable vertical list of sheet names. To install it (takes less than a minute) double-click the downloaded .workflow package and if necessary give permission at System Preferences > Security & Privacy. Also make sure Automator.app and Numbers.app are listed and checked at System Preferences > Security & Privacy > Privacy > Accessibility.
'Jump to Sheet' will now be a choice in the Numbers > Services menu. To assign a keyboard shortcut go to System Preferences > Keyboard > Shortcuts > Services and give it one.

Remember the in Numbers you can easily have many tables on a single sheet. So you really shouldn't have to have a large number of different sheets. But if you do have more than a handful of sheets either of, or a combination of, these two approaches can help your navigation.
SG