If you're adjusting the same lights repeatedly, you could set them up as a group.

It's more work, but you could also write a script that detects the current status of each light then sets the brightness if it's on. I use something like that for our smart porch lights that are on a smart switch - if the switch is off, turn it on, wait a bit for the lights to get on the network, then set them to the right color or whatever. (The switch normally stays on, but it gets turned off occasionally and it doesn't automatically turn on after a power outage.)

I haven't used other automation systems - I avoided them because I didn't want to get locked into one, until I found HA. I also have never thought to "dim a room" - actually I've never used entire room controls at all, they never made a lot of sense to me, but then I generally only have one or two lights in a room to control.