My personal opinion is that there are a lot of companies that take longer to pay than most shoppers, including me, would like. But most of them tell us up front what their payment schedule is and most of the companies actually meet that commitment or come within a couple of days. There are some bad companies who do not pay. Posts on this forum alerted me to Franchise Compliance and Freeman Group when they were slow-payers and no-payers, and both eventually went out of business, leaving thousands of dollars owed to shoppers unpaid. I think most companies pay the correct amount when they say they are going to pay.
One thing you have to keep in mind when you read on forums is that most of us are posting anonymously. We are strangers. Some discussions you read may be true, some may have some truth but not be completely true, and some may be outrageous lies.
That said, you should keep in mind that you are running a small business. It's important that you keep track of all the shops you complete and you should keep track of the payments when they come in.