2 days are enough. Plus it has become overly crowded, so you should checkout Conoor instead or you can take a toy train from Ooty to Conoor and spend more days in Conoor.
2 days are sufficient for this trip.
one must enjoy the toy train in Ooty.
other places are: lake, pine forest, tea gardens.
Connor is also near to Ooty.
you can think about that also