Is it a fact that face coverings slow the spread?

Yes, it slows the spread of lip-reading.

Assuming no COPD or asthma, etc., a sneeze will travel 150 ft/sec for 10 ft. So I could see a face covering reducing that significantly as well as a cough. So, theoretically it could slow the spread by reducing the amount of droplets floating in the air.

Masks don’t protect you, they protect others from you. If a significant majority of the population (the last 50 years worth of data indicates this is around 80% or so) wears masks at all times in public, you can decrease the environmental burden of a viral respiratory pathogen such that you can significantly effect the rates of spread and number of infections overall.

So the answer is yes, but it requires significant effort from the population of a given area. In practice, the answer is usually no because it’s hard to get anywhere near that number of people to wear masks. Now in East Asian societies, where wearing masks is already somewhat of a social norm and the “greater good” mindset is stronger, achieving this is less of a hurdle.

Theory....if truly effective-for those who claim so- I give you Exhibit A: Healthcare providers, the consummate breeding ground for secondary infections despite being the most infection controlled industry in America.

Face covering doesn't do anything unless it's a commercial respirator or a medically approved mask. Cloth facemasks are a hoax, con, ripoff, whatever you want to call it.

Watch this YouTube video from some Japanese research using lasers to show droplets generated with and without a face covering.

LINK