From the recent GTORB blog:

In both MTTs and Cash c-bet sizing deep stacked shifts optimal ranges but not EVs

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This blew my mind when I first read it but it makes sense when you think about it.

Half way down the post is MTT specific content (50bb starting stacks and different %pot cbet)

This was glorious insight:

From a players perspective this means that you have a fair amount of freedom to choose whatever c-bet size you like without impacting your EV significantly, even if your opponent responds optimally to your sizing.  You can pick a size that your opponent is likely to respond poorly to, as if they defend a range that is optimal vs a 50% size when you are c-betting 75% pot they will be making major mistakes with much of their range.