We didn't use any tutor, but we have done 4 mock tests to keep track, 2 local creative writing workshops (12 hrs in total) and a 3-month online revision course part-funded by a relative. Pm me if you want the details.
DS was well above average and in the top group of his year before we started the 11+ journey. He was an avid reader with excellent spelling and word knowledge. So we only had to give him chance to flourish not 'cramming'. Overall we did 30mins-1hr of work a day (school or 11+), he does his own reading, a bit more work over the summer holidays when we were at home.
Material-wise we used:
English and verbal - FPTP comprehension, Bond, CGP 10-minute test, KS2 comprehension and verbal reasoning 5 by schofields, Letts GL English tests. We didn't complete all sections in the books as we move on once he is confident of the concepts.
Maths - CGP 10-minute tests, Bond How to, Mental Arithmetic 5&6, Letts GL test, and random papers from the internet. King of Maths app for fun.
Non-verbal - CGP guide and 10-minute test, schofields book 4&5, Bond CEM paper and the online course.
I prefer CGP materials for CEM.
We have also helped a friend's dd who also passed Bexley. Her core skills was much lower when we started in spring. She used mainly CGP materials, some Bond SAT skills for the basics, Mental Arithmetic 4&5, and a few odd things here and there. She used a local tuition centre for mocks and tuition from June (2 hrs group tuition a week). I asked her to keep a vocabulary list and a notebook of study points, as she was making the same mistakes again and again. Overall she was doing about 1 hr of work a day, more over the holidays. She also attended the same creative writing workshop as my DS.
Hope it helps. The work wasn't too time-consuming but it is more about addressing knowledge gaps and weaknesses. Both children were motivated and wanted to succeed, and I think that made a big difference. Pm me if you'd like more detail on the local centres that we used.