> How many years should a company wait for an underperforming employee to perform?
Perhaps wait until after their spouse has died and see if they recover? Even the idea of an "underperforming employee" is specious at best.
This is why I love Italy and France, it is night impossible to fire someone for things like this from tech companies. Of course, they also don't have to worry about going bankrupt due to medical issues. They understand there is more to work than meeting the numbers. It is something you spend 2/3rds of your life doing, and other countries honor that.
[Oh, and also COBRA can cost $3000-$5000/month for shit coverage. Once you run out of money, they come for your stocks, retirement, and house. Source: I incurred over $100k of hospital debt AFTER INSURANCE from an assault that left my arm paralyzed. Why? If the hospital charges more than 125% medicare costs for the procedure, my $700/month Gold Plan didn't cover it. I was let go due to 6 months of absence from work, and then while unemployed and needing physical therapy, the hospital sent a request for tax statements and they began the process of a lien against my property. A lawsuit ultimately saved me, but if I hadn't been a victim, they would have taken everything. Fucking american healthcare is a joke.]