The other thing to think about is - sometimes people will 'price you out'. I've over-charged for corporate jobs simply because I didn't want to do them.
Unless you have a good working relationship with someone, they have absolutely no reason to give you any kind of discount. Myself, and many of my colleagues, have seen the way low-budget indies can go and how some can turn horrible, and some Directors can expect you to do everything, including 100 things that aren't in your job description simply because you're getting paid etc. etc.
Not all are like that, but you can't get a sense of how a set will go down unless you know the people. That's why you charge a full day rate. Because at the end of the three hours when you've only shot two shots out of the fourteen you're meant to have shot, and the Producer asks if you can stay for 'just another hour' and you end up staying for another 7 whilst the Director figures out what he wants - well, at least you've been paid for a full day and don't need to try and squeeze it out of them.
And then there's all the other points on top of that I made before.
I'm not saying all indies are like that, but you end up doing enough of ones that are to make you want to charge full day rate all the time - and you get to a point where you're getting enough work that you don't need to take every job that comes along, and certainly not at a heavily discounted rate.
Anyway, hope your shoot day went well