Excuse me, but how does a spread offense reduce the amount of time an OL has to hold their block? The spread is just a formation, nothing more. The Houston Oilers were the last team team to run a spread offense full time, and I do not remember at any point anybody saying one of the "bennie's" of the spread was the reduced amount of time an OL has to block.
Now, if Chan is going to implement a 1-2 read/progression type of offense, then yes, the amount of time the line has to hold their blocks will come down.