Fallacy One: You have to offer payment terms
Fallacy Two: Your clients will be in an uproar if you change this
We had always asked for payment on the first of the month. Eventually we switched to credit card only on the first of the month. Almost zero push-back. For clients who didn't want to do that, our terms are three months in advance by check. Zero push-back.
Next we asked to be prepaid for all hardware and software. After all, why should we be out of pocket for tens of thousands of dollars of someone else's equipment? Zero push-back.
As for projects, we asked for at least 50% up front and milestone payments for larger projects. No push-back. Finally, we asked for people to pre-pay blocks of time so that weekly minor invoices go away and we just chip away at prepaid time. Zero push-back.
The point is: These are very reasonable terms. And they can make a huge difference with your cash flow. My latest SOP video talks about some of the specifics of setting up "terms" and making your exposure as small as possible.