Surely evidence of what works can only be gained from testing your assumptions.
Many of you are no doubt familiar with Steve Krug’s seminal work on usability ‘Don’t make me think’ now up to it’s third edition (Don’t make me think, revisited, 2014). However you may not be aware of the follow up work ‘Rocket Surgery Made Easy’ . This basically provides a how to guide to do continuous usability testing with a small sample size of around 3-5 every month. This has two budget options for do it yourself testing. The low one which I costed in one of the organisations I have worked in came in at about $3000 the high one I didn’t cost but lets add a bit to Krug’s estimates (time has moved on) $5000-$8000.
This is still a relatively small spend and who knows you might even find the 300 million dollar button issue at your company.
At the very least it will help build your Return on Investment (ROI) justification for things like improving the staff directory search, making the general search better, etc.
Rocket Surgery Made Easy by Steve Krug: Usability Demo - He even has this video showing usability testing in real life. If you can play this video to your decision makers it may help them get engaged with the process.