Actually I believe the theory is roughly 90 seconds for any pilot to completely lose control in IMC if they have zero instruments to rely on. No matter how experienced, the inner ear tells us what we feel, but it may not always be what is happening.
For example, flying straight and level, you feel 1G. That is one times the force of gravity. A shallow banking decending turn also feels 1G, and being completely inverted, pulling slight back pressure and rocketing towards the ground feels the same. Without visual cues, ie. able to see out the window, or have instruments to rely on the pilot has no idea what is actually happening. Hence the accident rate.