As a freelancer, I’ve come across this a lot. I mostly work with other web dev shops, and in the main they’re pretty good payers (albeit usually exactly on time, rather than early). I’ve had clients in the past who have been horrendously late with payments before (6 months late in one case), and I’ve adopted a strict policy now that if I get messed around on payments, they drop down my list of priorities (ie if they come back for more work and someone else who pays promptly is also asking, the good payer gets preference), or in the extreme cases, go on my no fly list of agencies I’ll avoid working for unless they sort themselves out.

For smaller companies I can sort of see why they’re sometimes late, they’re normally waiting for their client to pay them, so that they can pay their freelancers, but that said, they should manage their cashflow so that its not an issue.

Whenever I sub out bits of design work to other freelancers, I always make sure that I pay them promptly, preferably as early as I can after the work’s signed off. Its meant that I have some excelent relationships with some really good folks who will always make an effort to squeeze any work I offer them in, because they know they’ll get paid with no fuss.