Do you have 300 workers in your local pool? That sounds like a rather large amount! You can ask your pool for as many workers as you want, but it will only give you as many as it has.
e.g. I used to set mine to ask for 100 because I didn't want to limit on deployed machines to the number of cores I used to have on my own machine when building an executable. It would still only open 8 cores though if that is how many I had.
