Most casinos will hold a slot for you while you go to the restroom, take a short break, or even go on a buffet run. Just ask a slot supervisor to reserve your machine and give a specific time when you will return. Don't chain yourself to a cold machine, even if it is your favorite. Because the longer you stay on any slot, the more time the machine's built-in mathematical advantage has to work you over. This is how casinos build mega-resorts.
Time always works on their side, and they have a mathematical edge on every slot.
Just because you're only playing slots, you still need to set a loss limit on your bankroll for both your trip and each individual gaming session. Divvy up your wad per playing session, discipline yourself and stick to it. I'll come clean here. I don't play slots. Simply put, locals don't play dog machines.