it looks rubbish because they have used two cut ridge for the mitre and run up to it.
if the actual mitre cut was a whole ridge, then the second one back a smaller cut.
Your roofer is almost correct ....just needs think smarter. don't cut to a point, but to a radius
second tile course down , 7th tile from hip has a channel off, needs changing
by the way the you tube link does not apply here, they are using half round seg ridge and third round hips...
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