As a rough, general guide, you can expect around 250kg from small burr grinders, 300kg from medium and up to 350kg from the larger burr grinders. Conicals, such as the large mazzer and compak run between 900kg and 1.2 ton, although I have a cafe running a pair of K10 conicals and we can't seem to get more than 800kg from genuine burrs. Genuine burrs seem to last almost twice as long as 3rd party burrs. Only use kilos as a prompt to inspect, because inspection is the ONLY way to know for sure - and that means removing the top assembly to get a good look at the burrs. Unfortunately, most people don't know what the approx. wear point is on the burrs, so you may find like I did on a recent K6 that the original burrs after 500kg were still fine, but we replaced them anyway. K5's use quite a small set of burrs, from memory I think they are < 60mm. The beans and barista techniques play a major part in the wear pattern. I have a customer who grinds our house very fine and doses low, so he chews through blades at almost 1.5 times the rate of comparable cafes. How a bean is roasted is very important. I have just started supplying a cafe who were previously getting their beans from a local "micro" roastery using a "low-end" drum roaster. We found the beans from their previous supplier quite dark roasts (much darker than mine) in external appearance and extremely hard to the point I believe they were not adequately roasted, e.g. dark on the outside and very light on the inside - the color of the ground coffee was a complete contrast to the exterior. The subsequent effect of grinding these beans over many months caused the burrs to wear at incredible rates (along with highly inconsistent coffee). The customer was usins a new grinder with the factory fitted burrs and it lasted a woeful 100kg - on our advice, the customer looked at the burrs and it was "game over". At 150kg, I would urge you to inspect the burrs. You might also gain some insights by trying a completely different pack of beans not roasted by you to see if you can consistently get the shots to match back-to-back. This is a process of elimination.
