Lose binding screw. What next?

So it's last Saturday, and I'm skinning up Mt. McLoughlin with a couple buddies. I ski Plum Guides mounted on Binding Freedom inserts. For the first time ever, I neglect to tighten my binding screws before heading up the mountain. About halfway up something doesn't feel right. I look down and, "Oh sh**", three screws are missing from the toe piece on my right ski.

I manage to find one of the missing screws nearby, so now I have two screws for one toe piece and still have all four on the other. Figuring two toe pieces with three screws is better than one toe piece with two screws, I transfer one screw from the opposite ski. However, I sat there for a good 10 minutes contemplating the optimal screw placement for averting disaster on the way down. I eventually settled that the rear inside screw of each toe piece is the least important.

I skied down with three screws in each binding without any issues. Crisis averted, lesson learned, and cautionary tale to those on inserts (no doubt won't again forget to tighten the screws or get caught without extra screws in the backcountry).

My question for the group (especially engineering types) is this: If you have no choice but to ski while missing a single screw on a tech binding, which one is most expendable?

Is that protocol to tighten insert screws before each tour? I've never had a problem with them loosening up

I have always tightened, but that's in part because I go easy on the Vibra Tite (thinking that the biggest concern is backing out the inserts when loosening the screws). Had some minor loosening once before, but nothing like this. Given my experience Saturday, I'd recommend at least checking (if not tightening) each time and keeping extra screws handy.

And I will probably change my policy on Vibra Tite...

I've never had a problem, but did indeed back an insert out last week when moving a binding to another ski, so your Vibra-tite policy has some merit.

No real idea on which screw is least useful, but I'd guess one of the back ones (or the front center screw on an older Dynafit toe).

I've never had a problem, but did indeed back an insert out last week when moving a binding to another ski, so your Vibra-tite policy has some merit.

Thanks, Marcus. That raises another question: For the backed out insert, do you simply re-glue? Or do you have to helicoil?

We've been running skis without threadlocker in BF inserts for about a season. They tend to need rechecking every few days; after the first retightening, one or two will need a quarter-turn or so on each recheck.

On the five-screw toes, I'm happiest to leave out the front one if a screw were to go missing. The rear inside screw seems like a good guess to omit, if it comes to that.

My repair kit includes a couple of spare screws and a matching allen key. In a pinch, it can be possible to cram a straight screwdriver or awl into the hex socket, but it nerfs up the socket for hex-key use in the future.