Check your manual on this but I think the accepted oil consumption on the 690 is 1 liter per 1000miles.  I think that's way too much even for the first few thousand miles.  My engine was consuming oil too but just a little.  I needed to rebuild the entire engine for another reason.  I did all the work myself so I know the engine very well.  The piston top was pretty much covered in a layer of carbon.  Whether from the worn valve seals or rings I have no idea.  But the bike did not smoke according to riders behind me over the 16K miles.  During the rebuild I hand honed the barrel with a scratch pad in a semi-circular/downward motion. The top end got new rings and valve seals just because I was in there.  I just completed the WABDR and over the 1100 miles it consumed 0.04 liters of 10w-60 Motul oil.  Yes, I really did measure it after draining.

Why some engines consume so much is beyond my comprehension.  Everyone does break-in differently.  I'm sure KTM knows how to do it best.  I just rode it normally. Cold engine/hot engine. Various RPMs, some on paved country roads, some on highways, more on dirt roads and single track.  I will say that the for at least the early air-boxes they were prone to leak dirty air before filtration.  I had to silicone seal the filter frame / airbox interface and I also grease the filter and make sure the airbox / throttle body clamp is firmly secured.  Dirty air can ruin rings quickly.