A correctly installed wire nut is a gas tight connection.

I try to leave them pointing up to limit water collecting in them.

Nothing is actually required.

I think the OP is asking about terminations on a breaker or bar, not wire to wire splices.

When torqued correctly the typical set screw connection in a panel is also gas tight.

You do have a torque wrench or torque screwdriver for torquing connections I hope.

The aluminum wire debacle of the 1970s called called attention to the general failure to enforce torque limits on connections.

The need to use low temper aluminum on single wire connections (as opposed to stranded) heightened the problem.
The aluminum heats up, expands, and deforms enough to reduce the connection integrity. It shows up as screws that are no longer 'tight.'

The next cycle makes it worse since the connection is no longer gas tight and becomes mechanically inadequate.

Harder aluminum would have resulted in solid conductor cables that did not have adequate flexibility for their intended use.

I'm curious how many of the professionals here have a torque screwdriver and how often they use it.

I have a couple of AHJs that come through torque wrench in hand and spot checks, especially breakers and neutral and ground bars, but occasionally a receptacle.

The screwdrivers are enough of a PITA and overpriced that using a wrench is a good option.

As long as you only use straight extensions it still gives correct readings, and for larger values (like 4/0 clamps) is easier to use.