It will typically last long enough that it goes out of style before it needs replacing from excess damage.  

Depending on your interest rates you may be able to get a better return on your excess money than by paying off the mortgages.

Speaking as both an investor and realtor based in FtL, these small MF are very difficult to get into at the moment due to excessively high pricing leading to negative cashflow if you plan to finance them. 

Does your cleaning service stay at your units  long enough to wash/dry the comforters before making the beds or do you have a second set that can be put in the beds right away.  

As a Property Manager in a market where many owners choose to manage on their own, I've seen several examples of owners losing their homes or properties because their tenants did not pay or caused excess damage.

While that bodes well for opportunities, the out of pocket cost would be excessively high as well.

You may thing you're buying a vacant lot, but it has $100,000 worth of junk to haul off, or that faded letter on the window when you get up close and personal says "dry cleaner". 

This works reasonably well for many situations, but it can lead to issues when you happen to have a particularly wasteful tenant that uses excessive amounts of water and/or electricity.

Both me and my husband are currently working, so the excess, if we do have it, sometimes goes to one of our rental houses.

When you buy a property, and hold a mortgage on that purchase, the excess cash you have between rents and costs is a form of profit but the short fall is NOT a loss, it's additional capital investment.