I also use these cheap hygrometers as I compared them to two quality stations some years ago putting all of them on a wet towell to get as near as possible to 100% (method suggested to calibrate one of the quality hygrometer I received as a gift). The cheaper ones showed some +/- 5 variation. So I consider them secure and been using them for years now.
At the time, I used to live in a steel and cement block with wooden floors in fromt of sea salted waters, so humidity used to swing quite much at Fall.
This Fall, in another home and location, humidity fell quite slowly in my house (wood structure and floors) so that it is getting by 50% now though November was exceptionnally cold.
As I experimented putting a wet towell in the room to maintain humidity around 50% last Winter and it worked, I am doing same this year without humidikits in guitar cases. I will keep hygrometers in these cases to monitor the effect.
For my scaly Winter face, I use Aveeno cream...
and file down my calusses...