My rule of thumb for the last 25 years has been: Double how long you think it will take you to do your bit, then go to the next set of units. e.g. 5 minutes bec

My rule of thumb for the last 25 years has been: Double how long you think it will take you to do your bit, then go to the next set of units. e.g. 5 minutes becomes 10 hours 1 day becomes 2 weeks 2 weeks becomes 4 months When you write code it's easy to forget the testing, documentation, and process and people overheads of getting your code out of your​ head and into production.