In my house it's a lot. Due to the shower being in a different spot than when the house was originally built so the routing is about as inefficient as possible, there's well over 100 feet of pipe between our hot water tank and our shower.
How much time does it take? In the US almost all shower-heads and faucets will only use a maximum of 2.5 gallons per minute. For me the water will get hot in about 30 seconds. So I am using approximately 1.25 gallons of water. For me that is acceptable.
