A lot of parents of young students ask music teachers how many minutes their kids should be practicing everyday (or every week) at home. I always say it really doesn't matter how many minutes they sit in front of piano (or other instruments) and 'play' (not practice) the piano. It really matters HOW they practice and IF they are practicing practically, mindfully, efficiently and structurally on targeted materials. If they are practicing practically, mindfully, structurally and efficiently and paying attention to what the teacher talked about during the last lesson their practice time won't be too long (which is OK). But if they are not paying attention and just PLAYING pieces mindlessly for many minutes 'that practice' is not really helping them improve or progress. Also it's more important that they practice everyday even if it's a little than they practice a long time just ONCE A WEEK ! (Gee, it's even worse if they wait to practice until the next lesson time or wait to practice at LESSON !!! ). It's also important to review what we worked on during the lesson right away (either that day or the next day) so that they remember what we worked on and what they need to be working on during the week. It'll help advance much more quickly and efficiently. After they 'practice', they can enjoy 'playing' some fun songs. 'Playing', enjoying, exploring, experimenting, being creative are also all as important as 'practicing'. I wouldn't discourage those at all. But if your kids are taking lessons (meaning you are paying for the lesson, right?) it's more important to focus on HOW they are PRACTICING, not how many minutes they should practice.