Preps can have different types of motivation.
The ones with a linked senior definitely want most to go on there. For some, they need to do an exam and so will be prepped for that....and yes, probably more effort will be out into getting the borderline to pass, although most Preps would like scholarships too. Some Preps however get their kids a free pass into senior and they do t do the entrance exam. It avoids the stress but often the incentive to really push them isn’t there in the same way.
For truly independent Preps, it is worth knowing when most will leave as has been said before, those that go to 13, in the past have been accused of doing less for the 11+ but that’s less the case now as most testing is in yr6 even for 13+ entry.
Prepping for a wide range of senior schools and lots of different entrance exams is hard for Prep schools ..some do different formats of reasoning exams and the written or maths exams can be very different. It’s why people often forget tutors too, who will focus on the specific exam or exams being sat by that child. People don’t realise until they are in the process how much exams can vary. So Preps will give experience of timed work, perhaps story writing and maths papers, reasoning questions..but the specific paper or papers a child takes might not have been practiced extensively by the school. It’s often tutors or parents working with the child who will do that extensive practice of a particular style.
When you’re looking round Preps...and this is hard with a 3 year old, or even a 7 year old, ask very precisely about entrance exam preparation and for a description of the process and timing and regularity of any practice and about marking of work too. If the school feeds a linked school, ask how they level their children and the standard they reach by the time they leave in top and also middle set....see how they describe it. If it’s too vague, it’s not good.
I’m a fan of stand-alone Preps. I think the experience children can have in the,can be amazing. However, I’m not convinced many take the kids further in most subjects (actually some do in languages, but a lot don’t really) and especially in terms of prepping for entrance exams, although that’s their remit, most people would do better with a very focused and targeted tutor, rather than a more general approach.
I think times have changed, it used to be that nice children at 13+ Preps didn’t have to be really clever or good at exams and entrance wasn’t a big competitive thing, but about being part of feeder schools which were welcomed by the Senior. However, especially in London, the market is so competitive (unless you opt out with an all-through school which quite simply can’t really be so selective) that lots of children in good Preps won’t make the top schools. Perhaps parents want more for their money today..not just a lovely school in the country with academics being very much an add-on, but parents want the grades and the extra curricular and the uni entry and to say their kid went to a top 20 or top 50 or top 100 school etc.
When you find out a Prep isn’t quite what you thought it was, or the thing you spot which you don’t like is something you’d never even thought of before, it’s often very hard to make genuine progress with it beyond a few tweaks. Some of the things such as the maths not being really stretching can be cultural and systemic and all related to the incentives or lack of incentives which exist regarding proceeding to the next stage of education and schools or teachers being measurable and held to account on basis. State school ofsted reports and SATs have loads of flaws and created a culture of box-ticking and often perverse incentives, but in independents which are all through schools, epseocialy those without exams, those lack of accountability points of ways of measuring achievement have their own problems.