Came to say this.
You can’t mark everything, and it’s not about that, it’s about recognising who needs more help, and who needs more challenge. So, a lot of the practice work done in books, will be followed by group work/class assessment/plenary where the teacher will ascertain as a class who ‘gets it’ and who needs to attend an intervention with her 1:1. This isn’t going to appear in books.
Also, writing a comment which doesn’t further learning such as ‘well done’ in 6 books (Eng, spelling, reading, maths, sci, his/geo), for 30 kids, might be nice, but unfortunately, teachers just don’t have the time. In my school, it is explicitly written in the behavioural policy that teaches must not make such comments, as the biggest issue for head teachers is reducing their staff workload to prevent teachers leaving the profession.
And another thing to bear in mind, when marking a piece of writing, there will only be certain things the teacher is looking for (success criteria, usually written at the top of the page on a label). For instance, in one piece of work, the children might be demonstrating the correct use of speech marks, ‘tion’ suffix and paragraphs (plus all previous learning). So, it may appear that the teacher is ignoring certain mistakes, but that’s because they haven’t been taught yet.
OP, it’s wonderful how engaged you are! Keep talking to the teacher, your LO will reap the benefits of your involvement 😊