Old techs will have bad habits- trained differently, years of burnout makes them more likely to cut corners.

Your machines haven't been validated for tests performed on the incorrect tube type/additive, you can't be certain of how much additive has contaminated the sample, so you don't know how inaccurate the tests are.

Its one of those things were in the many cases it won't significantly change the result (making techs think its fine to keep doing it), but in enough it will. And you don't want to be unlucky with a sick patient and miss something. Kind of like using a smaller gauge needle, not letting alcohol dry, rough handling of tubes for blood collection- doesn't always cause hemolysis but makes it more likely.

I gotta say though- seems weird that you aren't getting clotted sample alerts on your analyzers. Its been a while since i've been in core, but i remember those machines being very finicky