Open plan is a bad idea
I'm a software developer. We have an open plan office and I find it really irritating to get any work done. The problem is noise. It is distracting. Programming requires a lot of concentration which is really difficult to do if there is distraction. To cope with this I (and I believe many others) tend to block out whatever goes on around you. The problem with this is that you loose the skill to listen. If a meeting goes on for too long, your normal behaviour takes over and you lock out the noice. This is not what you want. There should be war rooms to do the collabaration, and quiet spaces to do the work.
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