I totally agree with Caddyman about overheating loosening head bolts. On every engine that I’ve rebuilt or performed a head gasket or valve job on it always gets run for a while, shut off, and the head bolts are retorqued.
In almost every case those bolts are able to be nudged a bit more after a heating and cooling cycle.
I’ve also never had to redo one either.
Back in the 70s Subaru used to recommend a head bolt torque every 15k miles. (all aluminum engine)