No. I've been using N95s since the start of the pandemic and have spent a fair amount of time learning about them, e.g., reading the written material that comes

No. I've been using N95s since the start of the pandemic and have spent a fair amount of time learning about them, e.g., reading the written material that comes with the box of masks, and I've never seen that kind of recommendation. The written materials say things like, "throw the mask away as soon as it becomes stained or discolored." I use each of my masks for probably at least 10 hours before throwing it away, and I've never gotten covid except once (in Jan or Feb 2020) before I started wearing masks (in fact, before anyone in my country -- the US -- knew about covid). (I have to write "probably" because I don't actually keep written records of how long I have each mask on. I rarely have one on for more than an hour at a time.) I've used mainly 3M 8511 masks. The most important distinction between mask models is that some models have valves / vents and some do not. Hospitals use ones without valves. The lack of a valve means that the part of the mask that filters the air gets a lot more damp than it would if a value were present (because exhaled air is damp) which might drastically reduce how long the mask will last, so that might be why some hospitals instruct their employees to use a new mask for each new patient contact.