Sometimes a path change, or a server change renders a collection of MXD files to have broken links to the Data Sources. Depending upon various conditions it can take quite a while for the map to load. (And there are several ways to repair them, fortunately, although there is room for improvement here too... but that's another topic.)
It would sure be nice to be able to, for instance hold down a Shift key, in order to bypass the Data Source check process as a map document loads.
This has long been available in the Windows OS (hold down shift key, as the dvd loads) to bypass the Auto Play feature of loading a DVD or CD. Why not add this Windows shortcut to the ArcMap product too? This could be a real timesaver if all you need is to check where a data source is trying to load from, or if certain data sources are temporarily unavailable.
I don't need it all that often, but often enough and with enough layers that it would be a very nice bonus and probably pretty easy to incorporate.