Yes, that would be a good baseline IMO. Start with an apparently
"clean" population. However, the tests are extremely unreliable and just because someone doesn't test positive on Monday, doesn't mean that they won't on Tuesday. I think it's a good start, but hardly a firewall against the virus.
My opinion is that you need to take all the right precautions. "Deal with it" is how I've put it previously, but be prepared to address symptomatic individuals. Most are going to be asymptomatic, or have the sniffles at worst. A few will be more severe. We can't stop that from happening, but we can prepare for it. Therapeutics and preparation for the rare critical case are needed I'd say.
Overall, just do your best and deal with it. I had dinner with a first-grade teacher Sunday night. A whole different discussion, but her stance on the whole thing was interesting. She can't wait to get back in the classroom, knows that there will be challenges and perhaps some hazards, and said that she and her students would be as careful as possible "without masks". Like I said, a whole different discussion, but I enjoyed her perspective.