50% relative humidity is fine for wooden instruments (I have recorders, guitars, and mandolins.) I don’t think it is common, I have a soprano and an alto recorder that are pretty old, both purchased in 1974, and neither have cracked. I have just recently returned to playing recorder (haven’t played since about 1975) and they are both in good condition. Just re-oiled them the other day, and found this forum today.
