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Interruptions are to developers what kryptonite is to Superman—they kill productivity and there’s a significant recovery period. There are two types of interruption: the planned meeting and the one where someone walks over to your desk to talk to you (or if you’re unlucky enough to have a desk phone it’s when the phone rings). The random interruption is akin to walking up to a someone building a lego tower, kicking it over and expecting them to continue from where they were the moment before you arrived. The planned meeting is a lot longer and kills productivity before, not just during and after. So, there are two types of problem that need addressed here.