I recommend adding reward system, that can be used on daily/weekly/monthly bases.
so from 00:00 to another 00:00 - 24 hours
whoever plays the most in that day, 24 hours - will get the reward (command defined in the config file)
-The command will be defined in ONLY ONE configuration file of all subservers, because this reward system is meant to be used in both single and multi server mode (standalone spigot and bungeecord, of course bungeecord is available via using same mysql database)
-So what is needed here is to implement config option to make server primary or not primary, but only one server can be primary, so in config file of Playtime plugin there will be something like:
#Make this server primary server. What this means is that whenever reward system is enabled, the player who wins a reward by staying online that day the most will get reward only on primary server
-Also what really needed here is to have global broadcast of the player who is a reward winner and his playtime for that day - who stayed the most online in that 24 hours (or one week, depends on config options), so placeholder(API) for winner player and his time would be neat. (This global broadcast feature can be synced without having plugin on BungeeCord i guess because LiteBans has the same feature to sync broadcast over all spigot servers, so i guess this would be possible)