Solid body guitars aren't affected by the humidity as much as acoustics, though my Strat necks get pretty bitchy as the seasons change so I have to touch them up. Acoustics, being a lot thinner wood in the body, with lots of bracing, can develop cracks or warping if we don't have a pretty consistent humidity so I try to keep an eye on the moisture in the room. I have a '69 Martin D35 that I've owned since the early 70s, and barely caught it in time to avoid damage when the top began to bulge because of the dry air so that made me pay more attention.
I've used the humidipaks many times, and they work well, but, unfortunately, "out of sight, out of mind" applies and invariably I'll forget because they last for a couple months, and I'll open the case and find a shriveled bag of desiccant huddling under the headstock or in the soundhole.
So, I switched to room humidifiers. I've been using the
AirCare table-top unit for a couple years and like it. It's an evaporative humidifier so it doesn't cause minerals in the water to coat everything in the room, and it's pretty quiet. I'd strongly recommend NOT considering the ultra-sonic humidifiers because the minerals will go EVERYWHERE in the room, including inside your modelers and computer monitor and stick to the display causing it to become cloudy. I'll open a drawer or closet and still find that stuff on things.
I also have two small humidity sensors/meters in the room, one on my desk and the other on the other side of the room next to the guitars and cases, and glance at them every couple days to see what they say, and have the weather app conveniently placed on my phone and iPad, and the weather humidity complication on my Apple Watch so I have no real excuse for not being aware of what is going on humidity-wise.