Fairly recently I did 4 days of travelling, so I shall summarise it in terms of ticket checks.
I reported earlier up the thread about full checks on a Northern service between York and Hull, which was the only check I encountered on that day (first on the trip).
On the second day I was checked on the first Northern service of the day between Hull and Sheffield, on a service between Cleethorpes and Barton-on-Humber (and on the return working) and on a TPE service between Grimsby Town and Doncaster.
I was checked on the third day on a TPE service between Leeds and Middlesbrough (twice, although by different guards), and on a TPE service between Leeds and Hull (with an announcement over the PA at Leeds about how Northern-only tickets were not valid on that service and the manner with which my ticket was inspected, this particular guard must've been rather keen to say the least). Nothing from Northern.
On the fourth day I was checked by revenue protection going between York and Scarborough (and witnessed a Penalty Fare being awarded, although in that circumstance I believe it was perfectly justified) and was checked twice at Scarborough station, although I was not checked heading back to York. I was then checked on another TPE service heading to Leeds (at around Neville Hill), and that was the last check of the day I received.
I boarded several CrossCountry services and received no inspection of my ticket, and on no Northern services apart from the two exceptions I mentioned above (I even managed to do Newcastle-Whitby in one go without my ticket being checked). It would certainly be better if both TOCs got ticket checks up and running sooner rather than later.