These types of services are incentivised to over test and you may find many spurious results when you over test. Look up the term "incidentaloma". If you have to get a real doctor to interpret and re order these tests, you are contributing to the burden of the system rather than a "pre test". The specific example you mention is apples and oranges, since the FIT test is a specific validated screening test provided by government rather than a profit driven private lab. There is evidence it's not even that helpful as a screening test.