I've seen my share of blood during shaves. But my worst cuts shave was my very first shave at very young age. I Didn't know what I was doing and cut myself badly with a Mach3. Cuts and blood all over the place. My technique was SO bad and my lather was shave gel wasn't mixed with water that it made things actually worse.

I've cut myself plenty with my straights, but it's no problem. It heals quite quickly and it's usually a result of complacency.

Some rules help. I like to shave in the evening, but not after I have consumed a beer or glass of whisky. Although I can't feel any difference, but I notice my shaves become rougher after 1 glass of alcohol. This only emphasis my believe you should be well aware of what you are doing with your razor. It is razor-sharp after all.