One of the more interesting issues we encountered with Magento 2 production environment is the cron_schedule table growth.
A few weeks ago, one of our Magento 2 production environments was getting slow. There was constant CPU load on the server, mostly used by Mysql queries. At times, more than six duplicated cron jobs were running. If we disabled the default cron job, the server load normalised.
We started to debug cron jobs with flock. Flock creates a lock file for the lifetime of cron execution, which means that only one cron job could run at a time.