Bismihi ta'āla
No, it would not be considered extravagance, or waste, as long as you do not prolong your shower, wasting water and electricity/gas.
There is no shar'i limit for how long you should take a shower. It would just be common sense. A shower should not take more than 3-4 mins. The sunnah of the Prophet (s.a.w.), is the water used for a ghusl should not be more than the amount of a jug of water.
And Allah knows best