Most nursery owners/growers will tell you not to overwater your begonias. They will tell you that begonias do not like to be too wet.
Even if you seem to be having excellent luck with a begonia that you are watering daily. Even if you are blithely watering it from the top and it is thriving.
The day will come that your begonia will go away to that great greenhouse in the sky. When that day comes, you will repent that you overwatered your begonia. I tell you now…don’t do it!
Note: This begonia is doing well. Its brother is in ICU. One can only hope…