When using Magit (and possibly other similar things), there are numerous occasions (when opening Magit, when committing, when viewing the log, etc) when a new window is opened and selected, but golden-ratio is not triggered, so the selected window is quite small.

As a workaround, I've been doing the following. Probably inefficient, but works.

(add-to-list 'window-size-change-functions 'golden-ratio)