It is more than obvious by these comments that there is something wrong with these roku remotes. What you save in tv price you spend every week buying batteries, I gave in and bought rechargeable batteries and you have to charge them almost every day! Can we get a clear answer as to what is happening and what is going to be done about it?
A casual stroll thru this community will show that many people have this problem with their remotes. But there are also lots of people (myself included) that do not experience this problem. Is that due to some remotes being defective and others not, some Roku models being harder on remotes than others, or due to some other factor? I don't know.
I *DO* know that if you have one of the remotes that has an earphone jack for remote listening, the earphone amplifier in the remote is activated and more quickly draining batteries whenever something is plugged into the jack, even when you are not streaming anything. Make sure you unplug the phones when not actively listening.
Beyond that, I've only seen one external factor suggested that may affect this.
There is some evidence that one cause of battery drain for those with point-anywhere remotes that connect to the Roku via WiFi-direct can be use of a router channel that is crowded by nearby routers using the same channel. It's been suggested that the remote has to work too hard constantly sorting through the information packets from other devices using the same channel such that it accelerates the battery drain. This is more likely to be a problem in the more heavily used 2.4 GHz wifi band than in the 5 GHz band.
If you have access to your router's setup, try configuring it to use a different WiFi channel to see if this helps the situation. If you are connecting in the crowded 2.4 GHz band, channels 1-11 are supported. Channels 1, 6, and 11 do not overlap each other and so give you the best chance at reducing congestion, so try each in succession, although depending on what channels your neighbors are using, other channels in the 1-11 range may work best. Also, reducing router bandwidth from 40 to 20 kHz may also reduce interference.
Note that the optimum channel choice can be a moving target as neighbors bring new routers online in your vicinity, or reconfigure their routers to use different channels. I periodically use a wifi analyzer app on my smart phone that can show me which available wifi channels have the least congestion and change the channel my router uses accordingly. I don't know if that explains my battery longevity (usually 3 months or more with fairly heavy use) but it's probably worth a try to see if it helps.
Please report back to let us know how you make out.
I also think that some Roku devices (streamers and remotes) have weaker wifi signal/antenna sensitivity than others (by model, and infective quality testing in factory), which means remote has to strain to hear and also starts shouting. All of which creates strain and higher power use. I think the expresses also have thermal problems (borderline thermal design) which can contribute to connectivity issues (and sometimes WiFi stops working at all, game over, buy a new one).
Lack of 5ghz WiFi support in cheaper models limits options for a clearer signal, which also doesn't help.
Using a IR remote (Roku or 3rd party) is less convenient but has more certain battery life (not possible for sticks, but possible for any external box form factor device).