Substandard usage would be a huge problem in a hospital setting where you get extreme exposure and even a single-digit percentage loss in protection effectivity

Substandard usage would be a huge problem in a hospital setting where you get extreme exposure and even a single-digit percentage loss in protection effectivity means sure infection. For day to day civilians however, even if they lose half the protection, if everybody has that other half it's almost enough to stop the wave. Losing ten percent of three nines is huge, losing ten percent of coin flip reliability is negligible. (but a coin flip reduction in everyday infection rates would still be huge). I strongly believe that unnecessary fretting over clinical hygiene rules of mask handling is responsible for a massive adoption delay, or adoption gap even today.