do you regulate shower use?

Some hostels in particularly sunny areas only have hot showers during the day. These usually heat the water with solar power and don't properly store the heated water for later use. It's probably not intentional, but it works to regulate showers to some extent.

In the past, some hostels used to charge for showers with a coin operated system. I don't know of any who still do this today, but I'm sure there must be some out there.

Some hostels use flow restriction devices that reduce the amount of water that passes through the shower. They're pretty common, and can be found at most plumbing stores. Combined with a low-flow shower head that infuses air into the stream, the pressure is not greatly reduced. Sometimes people complain that the stream can feel like needles though, depending on the shower head.

Other hostels use push-button showers, where a limited amount of water is let out every time the guest pushes the button (30 seconds of water, for example). These are affective for reducing the amount of water that is wasted, as they are less comfortable and many guests will take shorter showers. Other guests, like me for example, may reduce your water consumption even further by moving to your competition out of annoyance at these types of showers. In the interest of guest comfort, I don't recommend them.

Incidentally, the chances of some tourist kid getting drunk and hanging out in your shower for an hour are actually pretty high, to be honest. In most cases though, you can take comfort in the fact that the water consumption is actually divided by two, since these long showers are frequently experiences simultaneously by couples. If you notice this happening, just cut the hot water supply. They will usually finish up fairly quickly. ;)