I don't agree with your argument about cover lessons, I'm afraid. Perhaps things have changed but when I was at secondary in the 90s, we expected all our teachers to be able to answer any questions we threw at them whether it was a cover lesson or not! That's my point, I would expect all teachers to be able to turn their hands to other subjects. If they can't, then there's we might as well just use cover supervisors and TAs who have much lower qualifications than teachers to cover all lessons IMO because if you don't expect the cover teacher to be able to do some teaching, then it's just crowd control. There is absolutely no shame in brushing up skills prior to a test, but the skills tests are about the level of the KS2 SATs so I just don't see why anyone should find them so hard. If we want to raise the profile of our profession and gain respect, then we need to demonstrate high standards across the board. Half the problems in secondary stem from the fact that subjects are usually taught completely separately from each other and there's a lot of blinkered teachers out there. Not all by any means, but the movement is towards the skills based, cross curricular approach so these basic skills are going to become increasingly important.