There are some applications that recommend periodic re-torque of the head bolts as preventative maintenance. I know that Yanmar diesel engines recommend it after 2000 hours of operation. Of course, these engines use a simple torque setting rather than a torque-turn.
Also John Deere used to require that head bolts be retorqued fairly soon after engine assembly. I don't remember exactly what the time period was, but it was just a few hours of operation. That requirement has been eliminated with the introduction of modern head gaskets, though.
I did stop an oil leak once by retorquing a head gasket. This was a Cummins C8.3 engine in a wheel loader. The thing was leaking oil out the fuel pump side- this was a trade-in machine. The cheap [censored] that I worked for didn't want to fix it correctly (new head gasket), so they told me to re-torque the head. These are torque-turn bolts, and you can't just click a torque wrench on each one to make sure it's tight. So I went in torque sequence, loosened each bolt somewhat... torqued it to spec and turned it the required 90 degrees. And I wouldn't believe it if I hadn't seen it- but it stopped the leak.
So while it may not be reccommended, I MIGHT try this as a last resort if I had an old beater that was seeping out a head gasket. Other than that scenario (or if it happens to be a Yanmar), I'd just leave it alone.
Though I will admit that I've been tempted to retorque the heads on my GM 3100 V6 engines. They have 178k and 219k respectively, and these engine are known for occasional head gasket problems (usually due to overheat though). If I ever have the valve covers off for some reason and I'm feeling brave, I may just give each bolt another 10-15 degrees or so. But I won't be going to the trouble unless the engine is already apart for some other reason.