Pitcher- what pitch to grip?

When the pitcher gets the ball to start his delivery, he needs to grab the ball in preparation to throw it or maybe attempt a pickoff. So, how should he grab the ball?

Conventional thinking says grab the hardest pitch to grab in your arsenal. If you throw a split- grab it. If you throw a change- grab it. Whatever takes the longest amount of time to sink in that's the pitch you should start with.

However, I've come to think lately that the pitcher should always grab a four seam fastball grip on the mound. The reason? The pitcher might have to attempt a pickoff rather than throwing home. The pickoff attempt could come quickly depending on whether or not the runner takes off quickly. Furthermore, if the pitcher is throwing out of the stretch and the catcher asks for a quick pick then it is definitely prudent to have a four seam grip.

With a four seam grip, most pitchers will be changing their grip on every single pitch. This isn't a bad thing. You either want to "dig" on every pitch or resist digging on any pitch. This four seam grip seems to be the most efficient method in which to accomplish deceiving the batter.