The 5 year career break is a bit of a red herring. I'd be interested to see the numbers on how many teachers actually take 5 years "as soon as they are made permanent" which is what I read in the paper. As far as I know, a teacher can only take as many years as they have worked - so a newly permanent teacher has zero years worked up. (I'm open to correction on that). It's definitely the case though that career breaks can only be taken in two blocks, so if you take one year and later another year, that's the end of the career break allowance. Also, the second block of career break can only be taken after the same amount of time has been worked up . (It the length of service before the first career break I'm unsure of).
Career breaks are granted at the discretion of the board of management and are considered based on the needs of the school. A teacher can't just decide they're heading off. Plus, career breaks are granted on a year by year basis so just because a teacher has been granted one (or more subsequent) year(s) doesn't mean they will automatically get the further years they apply for.
Once again, it's the government falsely allocating responsibility for failings in the education system that they are destroying.
Often, a teacher who does take a longer career break is a mother with a young family who cannot afford childcare because... the government is also F-ing up that sector too