If I need to make repeat cuts over a long period of time, I make a reference piece and label it with length and application. When I need to make more pieces, the reference piece is placed between a stop and the saw blade. My normal saw blade, Forrest, has alternating teeth so I have to set the reference piece on the correct tooth.
If I'm making a batch of pieces, I use a stop block I made using a MagSwitch. I do have to be careful to set the stop block so that the stock clears it well before entering the saw blade.