I have Roku voice remotes still that came with Roku Ultras I purchased in 2017 that take double A batteries. In my experience they were terrible at giving you battery longevity, I'd have to change the batteries every three months.
The newer model remotes I got with my new Roku Streaming Stick 4K players have smaller remotes that take triple A batteries instead. The main difference is they removed the 3.5mm jack on the left side where you could plug headphones in on the older double A remotes. I've noticed the new triple A remotes are smaller and lighter and feel better in your hand to hold and the batteries do seem to last much longer, I went about 10 months before having to change one of them.
I still use the older double A remotes for my older Roku Ultras but I no longer leave the batteries in the remotes when I am done using the Roku, I take them out and notice barely any drain. These remotes are power suckers and they drain the batteries a lot even when your Roku isn't in use or isn't even plugged in.
Both the older and newer remotes still have the annoying issue of randomly popping up battery notifications on your TV screen that you have no option to disable in the settings. And all of these remotes still have the terrible design of having the volume and mute buttons on the right side of the remote, so you can accidentally press them when trying to pick up the remote.
I've said it many times here, overall these remotes are very poorly designed and they need a completely new redesign, which Roku is unwilling to do.