Consider raising your prices. That Portland shop is booked solid because they're cheap, not because they're good. People see a low price and jump on it, but that doesn't mean they're happy or that it's a good business model. You could be turning away better clients who assume a higher price means better skill. Being constantly booked at a low rate just burns you out for less money.
But that shop being booked solid is the whole point... they're moving people through the chair and making real money on volume. If you're charging $15 and booked all day, you're probably taking home more than someone charging $40 with empty slots. It's a different way to work, fast and steady, and for some clients, a reliable cheap cut is exactly what they want. Not every business needs to chase the high-end market.
That bit about "a reliable cheap cut is exactly what they want" is probably true for a lot of people. I've seen plenty of folks who just want it neat and fast without any fuss. @the_morgan I get your point about volume adding up, but it's a grind, you know? Running at $15 all day means you're basically a machine, not a stylist. In my experience, you end up working twice as hard for the same money, and your hands and back start to feel it after a couple years. You might take home more cash short term, but that model usually burns people out hard.