Personally, I think one should age any tire, tubular or "clincher".
Fragile sidewalls go hand in hand with a supple tire.
Way back, some guys just rode "hard", they went on the same training rides as we did and punctured 3 times as often, same roads same time, different riding styles. The same guys also went through wheels way more often.
The newer race tires with black sidewalls might be a wee bit more resistant to sidewall cuts, but I am vain and don't like them. On bikes I bought with them, I must admit they are sturdy, but not a fun to ride either.