Hey it happens.... I have left many lipos at full charge for days, even forgotten for a week or more, we have bad memories sometimes. Also chargers SUCK at discharging get yourself or make yourself an actual discharger, I use the ISDT FD-200 but I also have over 30 Li-po's so its justified to buy for me.
The main disadvantage of leaving a lipo charged:
-#1 at 4.2 volts per cell your lipo is the most volatile and if ruptured will be extremely violent. At 3.85v per cell very little excitement if punctured just mainly smoke. At 3v per cell some lipos Ive had did literally nothing when punctured.
-Pack will start to puff cells
-Once cells start to puff they loose performance
-At some point the pack will become unstable and may smoke/catch fire
It's a great solution, i've seen a lot of people using this. Just be sure to remove the gasket because in case of fire air needs to be sucked in, otherwise a bad explosion can happen!