1st of all.... NEVER EVER speed up a head shave or a face shave for any reason. Shaving should be your "zen" time. Me time. A time to relax and 4get the rest of the world. It is your time and enjoy it. 
I have to agree with warhawk about rushing a shave. I can, however, appreciate that time is luxury that not everyone enjoys.
I take three different razors into the bathroom for every shave. A DE for my face, except for the areas around my mustache and goatee; a Bic Metal Guard disposable with a very narrow head for the close work around the mustache/goatee area; and my oft mentioned Bumpfighter razor which is exclusively used on my dome. Additionally I have to haul along my brush, my soap or cream of choice for that day's shave, my scuttle for the loaded brush, and my alum block.
I average one full hour from the start of my shower to the final cleanup and exit of the bathroom.
As to the issue of getting that BBS shave all over your head; I find that using the Bumpfighter delivers because I can apply a good deal more pressure than I could with an unprotected blade. It is a single blade system as is the Bic I use for my mustache, but because it is set a bit further back, it is nearly impossible to cut myself. I mean you would really have to TRY and cut yourself with it. All that being said, the additional pressure - not MASHING it onto my skull - can be applied without fear and I can also do extra passes without getting any irritation anyplace, including the back of my neck.
As Dave Chappelle famously said (I paraphrase) my dome is as smooth as an egg.
