With those shaving creams, I find that it pretty much doesn't matter what brand of blade I use any more, and I can shave in 5 minutes. If you really wanted to optimize on the margins, you could get a sampler pack of 10 different kinds of blades and find the one that works best for your skin chemistry.
Lathering the Proraso takes seconds, rinse my brush with really hot water and put some hot water in the Proraso tub for a few seconds before dumping it out. Swirl around the brush for a few seconds and it's good to go.
I typically wait until my facial hair is pretty thick before shaving too. I use Jack Black's Face buff in the shower, then Jack Black's Beard Lube and layer Proraso on top of it. I'd be interested how well my shave would be if I used the same method with a cartridge.
For what it's worth, Proraso works well with cartridge and disposable razors also.
Part of the time savings is going with a tubes of shaving cream. The cream (Proraso in my case) lathers quickly and consistently, and is vastly superior to the canned stuff.
In the end, after becoming fully adjusted, I find that safety razors are just as convenient, give a better shave, and are far cheaper than cartridge razors. It takes just a minute or two longer.