Story Dependency Chains

I'm sure I read somewhere that user stories are supposed to be independent of each other, we eventually took this and changed it to they should be independent of each other in an iteration so that they do not block other work in an iteration.

But surely embracing the dependency of stories gives us a much better estimate of how long it will take before a story is done, we essentially have to look at two metrics, the capacity of the team. i.e. velocity, when taking into account holiday etc how much work we can do in the time frame. And how long the longest dependant chain will take to be done. If there is 3 months of dependent chain time and only 2 months of work then we will still take 2 months.

Another useful measurement could be expansion, how much do our iterations normally expand due to bugs and other important last minute work? Its going to happen, there are always things that pop into the iteration, so rather than trying to pretend it won't happen, lets create a metric from it and we can try to reduce it as much as possible. We can easily estimate bugs or any added stories after they have been done.

So the time something will be shipped in is essentially the amount of effort of it and its dependant stories will take, plus allowance for our average expansion. This also relies on the stories in question being constantly active so either planning them into iterations correctly or not doing iterations at all.
These measurements can hopefully be adjusted though, hopefully by pairing/mobbing dependent chain work we can decrease the time it takes to get the work done.

Yeah didn't really gif this one...