Organisational skill is actually an entrepreneurial skill. I'm learning the hard way that there are two diametrically opposing skills you need to master for both running a business and programming effectively:

1. Skills in Creating 2. Skills in Organising those creations

The thing is, the Creating part is always exciting but it's disruptive in nature. The Organising part is boring because it's about taming or tempering the creation in such a way that it can be referenced later on (just like filing your invoices, or timesheets - yuck - but necessary).

Unless you've got a systematic method to organise your creations, you will always be alone with your ideas, find it hard to resume creative chains of efforts and ultimately flounder without profit.

Both in business and in programming.

Damn right it's the most important software development skill.