Why it is better to focus on one thing at a time, according to Ron Jeffries

Ron Jeffries((@RonJeffries)  of http://www.xprogramming.com/ on the yahoogroups scrumdevelopment mailing list some time back:

 Take a simple example.

The value of a project is attained when the project reaches a
shippable point. If we have two equally valuable projects, A and B,
each requiring six units of work, if we do them serially, it looks
like this:

AAAAAABBBBBB
______^_____^
Val             Va

And we get value after six periods and again after 12. If we
interleave the work — and by some miracle that doesn’t slow us
own, it looks like this:

ABABABABABAB
___________^^

And we get value after 11 periods and then 12. That’s worse.

Looks like a pretty good way to develiver more value faster, and to get out of our own way thanks to incremental development.

[image cred: alandd]