I just did some test and I found that if you create a scene, Setup to Insteon, On Level 100% and Ramp Rate 5 minutes, the device remain to the default 100% and ramp rate 2.0 seconds.
Then in the program I can set the scene to On base on my schedule and voila, it works.
The write to the device only happen when the scene is created but not on every schedule. So no need for the wait and no need to write back the default ramp rate.