I've got a Laserlyte trainer unit which goes into the muzzle. I bought it to use with some sensors that would make either a sound or visible light as a response. Between airsoft, dry firing (I make my own snap caps) and laser training, I would say I use the laser the least. I haven't prioritized drills lately, but that's just me being busy and it plays a part of it.
For the Laserlyte laser, I had read a review that the parasitic drain on the batteries when not in use is significant so I take out the batteries after every session. That's kind of a hassle to load them back in because they are *tiny*. Of course, that person could be wrong and I could try just leaving them in.
But it does fill in a niche. You see, dry firing without feedback will still improve your accuracy if done carefully, you just won't see the proof until next time you get to the range. (eventually your proof can come through tracking your own sight picture and sensation in your hands/fingers) Lasers help with downrange verification. Dry firing while point shooting very close doesn't really need verification of accuracy. Unless you really struggle with pointing. Dry firing while point shooting pushing the distance or accuracy I think is a unique area that lasers can help with. Your focus is already on the target, so looking for the red laser dot would not develop a bad habit in that case.
If you're working on fundamentals and trying to focus on your front sight, having a laser promotes breaking your front sight focus and sight picture to look for the red dot on the target. You can train that out (hard for a beginner), but getting some feedback (like sound) that does not require you to change your eye focus is preferable. It's a similar struggle that new shooters have where after every shot they will lower their arms to try see the new hole they made. Soon the grip, arms, eye focus start to go slack earlier and earlier affecting the quality of the shot. No follow through. Having someone else observe the shooter's laser placement and steadiness wouldn't have any downsides that i can think of.
But there are also some compromises between a hard front sight focus and target focus that I'm not an expert on, perhaps a laser would be useful for those too.