Would you ever build a house without using an architectural plan? You certainly could, but it would be a bad idea. Additional cost overruns and delays would be just some of the consequences.
This is like installing a radon system without performing Pressure Field Extension (PFE) tests and grab sampling to prior to installing a radon mitigation system. If you want to spend more money, be unsatisfied with the end results, have a higher risk of lung cancer, and not meet dead-lines, then hire a contractor that does not perform PFE and sniffer testing prior to the install.
Even if you are selling, the risk of not performing PFE and sniffer testing is significant. If you want to get the best system, then depend on PFE and grab sampling.
We perform PFE testing on every radon mitigation system we install. We perform pressure field extension (PFE) testing by drilling test holes (approx. ½” dia.) or using existing openings in the slab, applying vacuum to one of the holes and smoke to another hole to examine air-flow under the building. If PFE results are poor or inconclusive, grab sampling will be performed to help locate areas in the slab with the highest concentrations of radon. This assists us in providing the most efficient system design.