Well, you didn't harm anyone there. The amount of time that the actors have to work is balanced out by the amount of risk they take about getting paid. The ones who showed up at 9am may be annoyed at having to do a full day's work for the same price as someone who only did an hour's work, but it was safe money instead of risky money. The next time they get the call, they may show up at 4pm to need to do the least amount of work for the cash only to find that you* didn't need as many people that day and they end up with nothing.
The earlier they start working, the more they have to work for the money but the less risk there is for them not getting any money at all. That makes the outcome fairly even.
* Well, not you, per se, since you got fired for not being able to manage resources well and wasting the production company's time and money trying to round up extra actors whom you should have had there in the beginning and they'll be working for your replacement the next time, but the point still holds.
The earlier they start working, the more they have to work for the money but the less risk there is for them not getting any money at all. That makes the outcome fairly even.
* Well, not you, per se, since you got fired for not being able to manage resources well and wasting the production company's time and money trying to round up extra actors whom you should have had there in the beginning and they'll be working for your replacement the next time, but the point still holds.
