Underperforming engines, up to 3% short of required N1, temp limiting out of SHJ etc.
Sods law states you'll lose one of the good ones and the remain 1.5 engines will take you to the scene of the accident.
These problems (and a host of others) are all attributable to 'mis-handling' by the crew . . .
SO, if it's ONLY max ZFW, then no problem because the performance is predicated on losing the critical engine - I'm at peace with that.