I've had a set of the 600AX bolts for about 20-years now. I just carry it over from one crankset to the next...
I use a little blue Loctite on the cap just to make sure it's snug and won't go anywhere. And some graphite-grease on the washer between the bolt and cap; even if the grease dries out, the graphite still provides a lubrication layer.