All of it depends on the design and margins built into the design. Shear strength on an M6 steel 4.6 grade bolt has to withstand 4250 Newtons of force without any deformation to make the grade. That's about 955 pounds. Grade 8 would put you at 2600 or so. Regardless of which grade you should probably be using all 6 of them unless the wheel and rotor have an interlocking interface to deal with the forces and the bolts are simply there to hold them together. https://www.amesweb.info/Screws/Metric_Bolt_Grades_Strength.aspx
Racebike or streetbike? I may have missed that part. But me? Streetbike? Pff I'd let that shit slide. Racebike? Fix it. Others could be affected.
Here's the thing, though: they put five on there in case you lose one and end up with four without noticing. Now you decide to start with four assuming that you will notice if you get down to three. Maybe that story as well, maybe it doesn't. Why take the chance?
Tracks have ambulances on the ready for a reason, shit happens, why bother. Its not an argument to have inferior equipment. Piss poor preparation= piss poor performance.
For me, i think the exact opposite. Street bike rarely has stuff checked like this, race bike..wheel is off every weekend. Sometimes more than once. Putting warmers on and off all day its likely to get noticed. Just my 2c though. Ideally, get it fixed. Will it be fine for a few rounds till its repaird? Absolutely. Again... just an opinion.
The fix is pretty easy, even with a few ways to go about it. However remote, what could happen and what are the consequences of that? For you and others..... weighing both........Simple fix for the win. IMO
Dunno.....but here's one that's definitely not a KTM. Not sure if this is a Moto2 bike or a rain setup MotoGP Here's one of Vale's front wheels that you can clearly see underneath there only has a 3-bolt pattern. another another