A colleague of mine was building a house. He wanted the bathroom to have two showers, and he needed to rework the plumbing before tiling.
It had been a long week of construction work when the professional plumber finally arrived to install the showers and plumbing for the washing machine as well.
When starting with the work, the plumber had a brief discussion with my colleague. He wanted to know if there was a piping for floor heating in the bathroom. Of course, there were, that was one of the comforts of this design.
Before starting the work, the plumber decided to run a set of tests. He blew pressurized air through the pipes to see if everything was ok to proceed.
A pillar of dust burst through the floor — the heater pipes did not hold.
Had the LVI-installer performed his job with without first testing the previous work, we would have been looking at an extensive water damage in a newly built house.
My colleague would have had to renovate the bathroom and the adjacent room within few months of moving in. Now, they just got away with re-installing the floor pipes. Not a significant expense compared to the possibility of a real accident.
These incidents happen everywhere we work. People make mistakes and sometimes components can be flawed too.
So, please test. And do it early enough. It will save both your time and money.