There are a lot of good answers in here, but to compile them and maybe add some:<p>1) The time between payments gives you the ability to verify that the service has been done correctly and isn't in any way fraudulent. Adwords is a great example, they hang on to the cash for as long as they can because once they pay you, they can't take the money back.<p>2) Immediate payment, even if automated, doesn't give any opportunity to double-check things. If you're dealing with $10 items, maybe that isn't a huge deal. But what if your task queue goes crazy and redistributes tasks over and over, and now you've just paid somebody $10 every minute the heartbeat pulsed and now you've paid them $20,000.<p>3) Processing deductions. The more you can charge on a single transaction, the better of it is. If you're making many small transactions and are losing 30 cents + 2.9% on each one, that's 33% you're losing on a one dollar process. Obviously, higher amounts negate this, and Net-30 terms help to negate that even more.<p>4) I assume you're talking digital processing, otherwise, I do not want to be the guy that has to cash 30 checks when I could have only had to cash 1.<p>5) The most important, possibly, is interest. The longer you can keep the funds in your account, the more interest it draws. I once worked for a restaurant that paid well, but had pretty thin margins due to competition. They always paid on time, but very politely asked that you waited until noon the next day to cash your paycheck, as interest calculations 'ticked' every day at noon at the bank they used, and while it doesn't sound like a ton, the interest on the paychecks of a 30-person staff adds up pretty quick, and every penny counts.<p>6) Lastly, if you have to track these payments for tax purposes, the less payments you make the better. Rolling in everyone's accruals into one 'lump sum' for payment could easily be the difference between filing monthly taxes in a couple of hours vs. having to take days to file.