I’m a consultant and I have a client on an arrangement like this, where I don’t really do much actual work but just give advice. I structured it as an up front

I’m a consultant and I have a client on an arrangement like this, where I don’t really do much actual work but just give advice. I structured it as an up front retainer that I bill hourly against as I’m needed. I wouldn’t do it without a retainer because the extra friction of an hour here and there is not really worth it unless I can get a nontrivial amount of cash up front, which helps balance my cash flow while working on other longer term projects.