One of the popular current debates is whether the current summer school holidays (typically 6 weeks long) should be shortened and spread throughout the year more evenly. This has come about for many reasons but the main one being that the government and teachers / schools are concerned that pupils having some much time off in one go is damaging their learning ability.
Many teachers feel that students tend to forget a lot of what they have learnt prior to the holidays when returning to school. This means that they have to spend a lot of time recapping on subjects already taught to bring students learning and knowledge back up to scratch.
There are also arguments though that pupils do need this break to recuperate and that it actually helps them focus more when they return to the learning environment. It may be that the only way we find out what is actually going to work best for teachers and students is to trial a shorter holiday and analyse the results.