I'd really appreciate hearing about how other schools do this. We enter data for all our pupils every 6 weeks. However, I don't think the way we currently do it really gives us an accurate picture of progress and helps us plan effective intervention. At KS3, we use APP and assess various AFs throughout the year. So we might have a year 8 pupil who does well on a reading piece and gets a 6b, but then the next assessment is a writing AF, he's not as good at writing and he only gets a 5a. On paper, then, he's not making progress, but it might be that the next assessment is a reading one so he goes up again (so SLT and parents are happy) but in fact he's not a secure level 6 because his writing is still weak. The same happens at KS4 - we enter a mark for whichever piece of work we've done most recently, so it might be a mock exam paper or a CA. Again, that doesn't really give an accurate assessment of progress - because just because a student has scored an approximate grade B on one CA, that doesn't equal a grade B overall when the exam is worth more marks and assesses different skills.
What's the answer? I know ultimately the answer is to assess holistically as often as possible, but how do you do that without doubling the marking?