Gökhan

To understand it you need to know what the clutch and the synchromesh are each doing.

The clutch disconnects the engine from the gearbox input shaft, so that shaft is free to change speed.

The synchromesh is a small friction cone inside the gearbox that brings the gear you are selecting and the shaft to matching speeds before the teeth engage. It is what makes a modern gearbox shift smoothly instead of grinding.

When you shift without the clutch, the engine is still driving the input shaft. The synchromesh now has to overcome the engine as well as match speeds, which is far more than it was designed for. It can often do it — which is why the shift sometimes goes through — and it wears rapidly while doing so.

Synchromesh wear is gradual and invisible until the day a gear starts crunching, at which point the repair is a gearbox rebuild.

On doing it well: it is possible to shift cleanly without the clutch, and lorry drivers with non-synchromesh gearboxes do it as standard practice.

The technique is to match the speeds yourself. Ease off the throttle so the gearbox is unloaded, move the lever out of gear into neutral, adjust engine speed to what the next gear needs, and let the lever slide in when the speeds match. Done correctly the lever goes in without force and the synchromesh has almost nothing to do.

The key word is without force. If you are pushing the lever against resistance, the synchromesh or the dog teeth are absorbing the difference and you are wearing them.

Done properly it is not particularly harmful. Done impatiently it is expensive. And for anyone learning, the clutch is there and using it is free.

Where breakers are used tells you exactly where the trade flips.

You find them on circuits with high current and a legitimate reason to trip in normal use — power windows and seats, where a motor stalls when something obstructs it, and winches and similar accessories. In those cases a fuse would blow during ordinary operation and the owner would be replacing them constantly.

So the rule is roughly: fuses everywhere a trip means a fault, breakers on the few circuits where a trip is expected behaviour.

Worth also mentioning fusible links — a deliberately thin section of wire used as high-current protection near the battery — which is the same idea again, chosen for cost and simplicity on circuits where a proper fuse would be enormous.

There is a legitimate version of the argument that gets mangled into what you were told, and it is worth knowing so you can tell them apart.

Some manufacturers do specify replacing discs at every pad change, for their own vehicles, in their own service documentation. Where that is genuinely in the manufacturer's schedule, a franchised workshop following it is not inventing anything.

The difference is that this is a model-specific instruction, not a property of European cars in general, and it can be checked. So the right question is: "is that in the manufacturer's schedule for this vehicle, and can you show me?"

If the answer is yes, you can decide whether to follow it. If the answer becomes vague, you have learned something about the recommendation.