Plaster joins crack me up

Asked a while ago about what to do about these cracks that run along the apex but joint of our ceiling. Theory us that easy tape probably used rather than paper. Am think it will be relatively expensive to get a plasterer in to repair so started looking for alternatives.

Funnily enough, the plasterer we had in to do some other work suggested wooden strips along each side of the join. Any other ideas?

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A couple photos would be helpful please

I wouldn’t discount a plasterer. I had one in to help redo my ceiling joints which I imagine are like yours. It was well worth the cost which was less than I was expecting at an hourly rate. We ripped out the joint and scraped off compound, coated with PVA and he reset the joint all in a morning and an hour sanding next day.
You should probably backblock the joints if you can