NQTs frequently get Starters wrong. Not because they misunderstand some pedagogic concept, but because they misunderstand a basic planning concept: the payback principle. A payback ratio simply relates how much time you spend on something to how much benefit you get from it.
For example, if you spend 20 minutes planning a one-hour lesson, then the ratio is 1:3. If you can deliver that same lesson to two classes, then the ratio goes up to 1:6. If it can survive unchanged for three years, the ratio goes up to 1:18 - this means that it was a brilliant 20 minutes of planning.
Unfortunately, some teachers get things very wrong. If you spend 20 minutes planning a 5 minute starter, then you'd better make sure it can be used time and time again; a brilliant lesson introduction which is based on yesterday's X-Factor loser is likely to have a ratio of 5:1 (it takes five times longer to prepare than it does to carry out). It may be a good starter, but it's just taken way too long to plan. This is fine if it's a lesson observation or a really difficult class, but you just can't spare the time to do this routinely. Starters need to be short, which means they musn't take too long to plan and prepare.
Another - linked - problem is planning in chronological order: this means that a teacher starts to plan a lesson by planning their starter. OK if it can be done quickly, but if you get stuck then the whole 60 minute lesson gets stalled because of a glitch at the start. This is a common trigger for a creative block, stalled planning and FRUSTRATION>
To help with this mess, we offer you A Year's Supply of Starters here.