In France, Germany and Denmark (where I have been employed) you can do this for something like 10 to 20 days (usually 10 days). But sometimes, you can do this but some of them need to be taken within 3 months of the next "holiday" year (the holiday year starts usually 1st of April).

It means for example, that with the about 11 holidays + WE + 30 paid holidays + 10 days from the year before, you can get a year with 51 days "unconnected".

I don't know what the general rule is here. My employer allows my to save a certain number of vacation hours for the next year. However, these leftovers can only be used the next year. In other words, you cannot save hours multiple years, and then take a year of ;).

Only a limited number of days. Currently, 6 days, I think.