We do our projects on a fixed fee basis, and usually get 50% up front. Sometimes we do 1/3 up front, 1/3 after a milestone, and a 1/3 after completion. We are on a construction project, and that is done on a schedule of values where we invoice based off Milestones. I can work with that because we know there are funds available, and the payment process is very structured. We know when we will get paid and can plan around it.
I really don't care how it looks, that is how we operate. I do what is good for our company.
Recently, we had a management company sign a contract on behalf of their client, and told us a deposit check was being processed. Great, we put it on the schedule, ordered all the material and were ready to go. Guess what, the client and management company broke up and never told us. Only after we asked about the deposit check, were we told they were no longer responsible for the project. Now we have the material, and still trying to sort out the details from the new management company.
Vendors offer Net 30. Depending on the project, you are going to order the material, wait a few days for shipping, stage it, then start the project. There's a pretty good chance, you won't even be done with the project before your invoice is due, let alone be paid.