Reminds me of the saying: If you want it to rain dig a hole. (or trench).
Its always a challenge planning and scheduling work outside and dealing with the weather. Its frustrating but the rain will stop and your project will continue.
Except when you go to other peoples house without Toto's you end up dropping the seat and scaring the **** out of yourself.
I would second on checking how quickly the flapper closes.
My house is a 14 year old modular with two Briggs low flow toilets. They kinda **** even after fixing them...