There is a certain logic to what Robbiebox is saying, but I believe it"s slightly flawed.
With 300 plus players the number of drop outs would be comparable to a field of 150 for the first two thirds/three quarters of day one. It would then slow down due to one factor - the number of chips in play compared to the blinds.
With a greater number of chips in play, those considered short stacked ordinarily, wouldn"t be when compared to the blinds they have to pay. Less players would feel forced to push.
To counter that, the timings for the levels would have to be dropped to 25 or 30 minutes, to ensure that the short stacks at the back end of day one felt compelled to push.
I"m not sure that changing the timings would be good for the events.