Well it really depends. Here are 2 routes for example.
IAH-AUS - 733
The 733 will fly probably up to 6 routes per day because it will fly shorter distances and is easily maintained. It is meant to let pax board, get in flight, let pax off, and let another load on very fast. Planes like this include the A319,A320,A321,717,727,737, and 757.
The 772 will take a lot more money to keep up and thus, fly less routes per day. The 772 also flies the long haul routes and thus that route pretty much occupies that plane for the day. The plane is prepped before departure for hours by hundreds of people all together including ground crew, cleaners, mechanics, etc. Then pax board. Then the pilots check everything, etc. Then they take off for a long haul. Usually (like with CO at LGW) there is a flight from LGW-IAH shortly after the IAH-LGW route lands. It is not the same aircraft usually. Usually airlines keep the plane that flew that route earlier say IAH-LGW the day before, to fly LGW-IAH the next day, so the cycle continues. CO at HNL is an exception. CO used to keep DC-10s in hangars at HNL and after a flight, they would get fully looked at until the plane was 100% okay, then it would fly again. Of course, at hub airports, like IAH for CO, aircraft can be brought in and replaced easily. After the longhaul flight, the aircraft is looked over for stress, etc. Hopefully this answers your questions.