I'm not very familiar with situations in every country ;) A bit in Belgium and Germany. In Belgium it is like the Polish miners: if certain groups are involved, I think the effect is felt in agreements in the end. But that is still what is needed after all: agreements. No union wants to strike forever, there is money to be made after all, striking is expensive for the workers (which is a main reason unions exist at all). Workers and owners share similar goals, don't forget: work, make money, be wealthy. Strikers generally aren't disputing that, all they are disputing is how much % of the wealth goes to whom.

If the Metallurgy takes to the street, politicians are scared. If farmers/truckers block highways, politicians are scared. If dockers go to Brussels, they bring fireworks (also literally), politicians are for sure scared of them. These do happen to be some of the best paid 'low education' jobs. Is it a coincidence?

The magic is, and it happens rather rare indeed, that all of them strike together, you need the dockers supporting the nurses etc. Unfortunately I think the battle against the pension age is lost everywhere. The EU serves as a divider by the way: we're always told we need to earn less of pension later or ... because "all our neigbouring countries are more competitive in this field!". Then you tune in to the media in the neighbouring countries: it's the same fairytale. The capital succeeded in dividing the workers across Europe, unions across EU-inner-borders extremely rarely join forces, and it has become a major weakness of the unions in EU today.

In my experience the general public transport strikes do more bad than good to the workers, for sure in the long run. These strikes are just way to common, general opinion outside the profession is that they are already generously treated for pensions, holidays, etc.

Then there are a few groups of workers... they barely have to announce a strike and they'll get what they want. One group is the train drivers (not all public transport, just the drivers). Another are the maritime pilots. If these strike, nothing moves. All ships/trains are blocked and the entire economy bleeds like crazy immediately.

But no, I can't provide you with any concrete evidence of protests actually having forced a better deal than if no protest would have been held. It's a gut feeling i guess. I don't think there has been a lot of A/B testing on this, tricky to organize ;) And between countries cultures and striking traditions are just a tad too different to be able to compare it easily.