Interesting. I've never seen anyone put screws through their gang nailing.
That would do a good job keeping the gang nailing from sliding side to side during a storm situation. Good addition for those gang nailings.
Back in the day, truss's were all put together with pieces of plywood or wood blocks. Gang nailing has replaced that style and lost it's deeper penetration due to ease of installation and lighter building techniques.
@Dave_J Did that one house install screws on both sides of the truss and into each gang nail? Pinning both sides to the truss members.