Should you re-tightening head gasket bolts after 150k-200k mile?

I wouldn't touch it. For starters it's not trivial to dig down far enough to access the head bolts. Never done a head gasket (knock on wood), but just off the top of my head, think you'd first have to first remove:

coolant
water pump
oil filter bracket
engine mount
valve cover
"balancer" pulley
timing chain cover
timing chain and guides
timing chain tensioner
cam shafts
cam shaft cradle
rockers and associated

Then carefully scrape clean mating surfaces, apply various form-in-place gaskets, replace gaskets, reinstall the above, refill coolant.

To check something that's almost certainly as it should be?

If you were going through all that, I'd go the extra step, replace the head gasket, lol.

The poster you link had a head gasket replacement fail soon thereafter, likely because he screwed something up in the process, or didn't touch the EGR.

 

The drain plug bolt is NOT a stretch bolt. It is not, and won't stretch, unless over tightened.

To "retorque" the head bolts, you'll have to loosen them all, in sequence, the tighten again,
in sequence. Which will allow cools to leak into the cylinders and oil. Thus ruining the head gasket.

The head bolts are stretch bolts. After initial torque, there are 2, 90 degree turns. Which
stretches the stretch bolt. There is certainly enough torque to secure it and keep it secure
to the block.

 

It's a 90 degree, then 45 degree turn.

Yeah bottom line, it's NOT sensible to do this, just on a whim.

Full disclosure: I've never done a head gasket, but have an inkling of what's involved.

 

Head Gasket Bolts & Torque Head Bolts | Fel-Pro Gaskets