I would like to add that I believe that most people will not and should not do 1rm tests.

People who have trained for some time know their actual 1rm which in itself has factors that influence it on the day such as sleep, food intake, hormone levels etc.

Even then trained individuals can fail their 1rm at maximum.

Untrained individuals belief of their 1rm vary wildly. Those who overestimate their 1rm at retirement age have much larger recovery times (and from my observation, more risk of long term damage) than the average 20 year old.