If your a gambling person, what is the average amount you feed a slot machine before deciding to change machines?

When I used to gamble I tended to observe for a little before playing, or try to find out when it last paid out a big amount. I also looked for the signs that a big win was likely. You tend to get a sense of how the machine is playing. The ultimate aim is to not end up trying to buy the jackpot, but instead finding the right timing and the machine that wants to give it to you. How much I would put in an individual machine at one time could vary, but it might have been up to £500 a week which would have been $750 to $1,000 depending on the exchange rate at the time.