As an ex instructor my take on this is as follows:-
You pay a 'per hour' rate for your flying or an agreed amount for a 45 hour ppl course. Included in that is the cost of the briefings because the PPL syllabus as per the JAR syllabus, includes a briefing before each exercise. (How else are you to understand what you're supposed to be doing without structured ground school?)
If you wish to pay for extra tuition then you ask for it and have it at a time separate to your flight training, ie when the wx is too poor to fly or on an evening. That way it is agreed what you are paying for (ie instructors time) and also you can pay for as much or as little of the tuition you need for passing the ppl exams.
If you aren't advised by an instructor that you will be charged for his time, there and then, I wouldn't expect you to pay.
There are some real 'suckhole' instructors around and sounds like you met up with one of them.
In this present economic climate, it's easy to say the schools are trying to fleece as much cash out of students but in reality, they should be treating the students with a bit more respect as that is where their income is from.
Find a different school Nathan. Sounds like they might just 'extend' your training, using the excuse you need further training and make more out of you than is really necessary. Think about it. If you're happy with this sort of practice you've experienced then carry on. Personally, I would change schools.
There are some really good instructors out there.