Yes, i can call these personal, opinion, no proof stories as anecdotal...because they are. I don't know you from Adam - so why would I apply any of your situation/circumstances to my own? Because you didn't tutor your son, then I should believe that I don't need to tutor mine?
There are so many more details that are not shared, and cannot possibly be verified. What is that persons definition of tutoring? You say they got in without tutoring - do you mean without professional tutoring, but the mother was doing 4 hours every night? What is that persons differentiation between a little and a lot of preparation? Is a little prep just 4hrs a day during Oct half term, or is it 6 hours every Sunday afternoon for a year?
Point being - be wary of people sharing their stories here and using that as evidence to inform your decision. Lots of people seem very forthcoming with their stories of getting in without tutoring, very few people willing to share what preparation/tutoring they actually did to get in. Unsurprisingly...
My advice is to speak with real life people. if not friends and people you trust who have gone through the process, then your school's head, your sons teacher, a third party educator (teaching assistant, learning enrichment coordinator) Show them sample exam papers for the school you want to apply, look at where your son's school work is and see whether you think your son will be able to manage the exam. And then, use your best judgement to decide what you are or are not willing to do to prepare him to get in.