Using multiple worksheets in a single file is a common Excel technique, but getting to the sheet you want can be time consuming. Right-click to the rescue!
Inside Office Online points out that if you right-click on the sheet navigation controls (the arrows in the bottom left-hand corner of the workbook), you get a pop-up list of all the sheets. Experienced Excel jockeys may well have known this trick for years—for me, it falls into the "why didn't I try that before?" category. I'm a longstanding user of Ctrl-PgUp and Ctrl-PgDn to move between sheets, but this is definitely a handy addition.
Hidden gems in Excel, part 1 [Inside Office Online]