You really have to plan to deal with things like this because it will happen.
This is exactly what revolving/lines of credit are for. Talk to your bank.
Source: have seen a business growing who had to deal with this. There is no way - no way in hell - you can scale a real consultancy business using escrows and ditching clients as soon as they don't pay. It's just not how most of the world works.
- Customer says they can only pay in 6-months time? Ok, you will route around it.
- Customer says they will pay next month and then ghosts you for several months? That's not cool. Particularly when it's peanuts for them, in the grand scheme of things.
I was personally burnt by the latter scenario. It was only resolved when they reappeared almost a year later, after I had stopped consulting altogether, asking me to find some other guy to carry on; I replied that I couldn't honestly recommend my peers a customer that doesn't pay, and lo and behold, two weeks later the money came in.
By this, do you mean clients tend to insist on long payment terms in the contract? Or do you mean they'll sign a contract agreeing to pay in 30 days then they only actually pay after 90 days?
That being said, project continuity is huge with large organizations and if you're opportunistic, there's always something to be fixed. They also pay well and are more likely to pay. That's the tradeoff for slower payments.