I used to do the few caps off method until I came across a 2.0 turbo VW that lost _all_ of it's oil at once due to a punctured oil pan. ( and was driven 3 + miles ). All rods / mains were perfect except for one that started to transfer bearing material to the crank. Ended up flaking the bearing material off the crank and doing a quick polish to save the engine. ( This was an in car repair and all bearings were changed ) Had this last bearing not been noticed / properly repaired, the engine would have come apart in sub 5 K miles.