The tech lead at my place has just burned himself out and quit after making a load of poor decisions. He reinvents the wheel over and over again rather than use

The tech lead at my place has just burned himself out and quit after making a load of poor decisions. He reinvents the wheel over and over again rather than use some prebuilt solution. I am going to have to maintain his undocumented, untested code. Experienced coders can be just as bad for over-engineering as noobs.