I do a lot of calfskin heads (more than 600 so far this year) because there is a big call for it here in the Northeast with the Fife & Drum community. I put thin heads on 16" and 17" rope tension snares that are played with sticks that would make a Vic Firth 3S look like a tooth pick and the guys playing them are doing 40 - 60 parades a year. Under those playing conditions I have seen heads last 3 or 4 seasons comfortably. What truly effects the heads (skins) is the humidity and moisture. Many F&D corps have two sets of drums, one set with calfskin and one set with mylar or kevlar heads for inclimate weather. If you live in a hot and dry or cold and dry climate the heads will be fine once they have adjusted to the room that you are playing in. When calf skin heads are played out in the sun they are going to tighten up from the heat but will only tighten up just so much and stop and will perform similarly in a cold room. When it gets humid or wet from the rain then the heads start to go slack and get sloppy to play on and that is when you will start putting heads through them. The great thing about playing bar gigs now as opposed to playing them in the 1940's - 50's is that we play in rooms that are climate controlled and have air conditioning so in many cases, even if the room gets hot it is still relatively dry.As for the heads mthemselves, the heads do eventualy dry out and don't have the same bounce that you would get out of new calfskin and in a lot of cases, picking up a vintage calfskin head and putting iit on a drum is like playing on construction paper. It will sound different than a plastic head but will also sound different than a new calfskin head and you run a much higher risk of putting a stick through it because it is dry. Hope this helps.