So the feature that I wanted to mention was the ability to Schedule Policy Installations with R80.20 (not M1). It is in the current public EA as well as the upcoming next Management Feature Release.
You can create a preset with multiple policies or multiple gateways in it. Then, you can either play it with one click or add a time object to schedule it to a time window.
This way you could install multiple different policies at once.
You can use this feature if you are a Multi-Domain user by logging into the MDS domain and going to Install Policy Presets.