Two or three hours of basic instrument panel familiarisation, throttle and mixture handling and even basic radio procedures on a synthetic trainer is a good cost saving measure. Effects of controls, climbing, straight and level and descending in the synthetic trainer can be of great value and you don't get airsick. Providing you are being taught by an experienced and good flying instructor in the synthetic trainer, it can save you at least three hours of expensive airborne time.
You should be able to go solo in the real aeroplane under 10 hours with previous synthetic trainer instruction. Providing you have a grade one instructor teaching you the whole time, an average student should solo by 8 hours.
It is when a grade 3 inexperienced new instructor is teaching you, is when the time to solo escalates significantly along with the commensurate costs. I have seen it happen many times.
The beauty of it is that if the weather is unsuitable for actual flying, you can practice in the trainer and enjoy a coffee break. Makes for relaxed and enjoyable instruction
Although the synthetic trainer is flying on instruments, nevertheless, the "engine handling" prepares you for the real thing. Disregard the point of view that use of the trainer will cause a problem with looking outside the cockpit in the real aircraft. It simply doesn't happen.
If you are a couple of hundred feet too high, or IAS too fast for the configuration during visual flight in the real thing, you have to keep an eye on the flight instruments to regain the desired state of flight. That does not mean to say you are "locked " on to those instruments simply because you had previously "flown" a synthetic trainer.
As far as dual taxiing practice is concerned prior to your first flight, well there is no doubt that not only is this entirely unnecessary - but it is a total rip-off and a waste of your money. Interesting to see if the instructor who does this taxiing "practice" with you, logs the time in his log book - even though the aircraft is not going to actually take off.
Seems to me that CASA should look closely at the practices of the particular flying school operator.