As an incredibly rough idea of what seems to happen in AJX a lot of the time; a 3 hour flight, during which time cloud was flown through in the climb, descent and (usually) during the cruise will normally end up with 30 minutes of IMC written in the aircraft log/your logbook. There's often 0 and there's quite a few >30 minutes but 30 mins seems to be a recurring theme
I agree with what TD has written and it is pretty irrelevant when the autopilot is engaged whether we're in cloud or not and the logging of IMC was certainly meant for when an aircraft was being flown on instruments and not merely managed/monitored. One day the authorities may get with the times and then, 100 years later, the JCAB will catch up. In the meantime I suggest 50% of block time might be somewhat exaggerated. If it helps, I'm just shy of 20000 hours and have a shade over 3000 hours IMC in the logbook; so 15% versus 50%.