I've found most blower motor failures are due to unbalanced blower wheels (bearings go bad) or overheating (windings burn up). Both caused by excess dirt in motor/blower wheel.
Prior to my 'Repotting Career Change' to HERS Rater, I served as Administrator of a 36,000 sf skilled nursing facility, from 1983 - 2009. I purchased a lot of new furnaces over the years. We were heated and cooled with residential style hvac units. I had 21 units ranging from 2 tons to 5 tons of AC.
I have replaced units due to cracked heat exchangers, and bad compressors. I have replaced squirrel cage fans that got out of balance. I have replaced units due to age and due to Hail Storms.
I have not experienced a blower fan motor failure, or heard of them among my fellow administrators. I have experienced motor failure of the ventilation fans that are required by state and federal law to run 24/7. These routinely fail, and must be replaced.
The ventilation fans meet a requirement to maintain a depressurized difference from common areas to patient rooms, to bathrooms. This is an infection control issue, and secondarily a odor control issue.
I think running a 400 CFM (per ton - so 1200 - 1800 CFM) fan to provide fresh air instead of a 60 or 100 CFM balanced ventilation system is not good building science. it is certainly not good energy efficiency and energy management.
Most furnace blower fan motors are only 3/4HP to 1.5HP and only draw .5 amp to 2 amps at most. The coast of running that 24/7 a year is only $50 for the year if your electric company charged you $.09 a kilowatt hour. By turning it off and on with it in on auto you might save $5.00 a year. The coast is minimal.