Most paycheck parking examples assume a tidy salary landing every other Friday. Plenty of the people most interested in this strategy don't live like that. Commission months that swing by thousands. Seasonal businesses. Invoice income that arrives whenever clients feel like paying. Does parking still work? It does, and in some ways it fits lumpy income better than a savings account does, but the setup has to respect the lumps.
Start with your floor, not your average. An average lies to you when your income swings. Add up your last twelve months, sure, but then find your two or three leanest months, because that's the income your baseline budget has to survive on. A budget built on the average will spend money in March that doesn't arrive until August. We covered finding the real number in Find Your Real Monthly Surplus, and for irregular income you use the floor.
Then let the line of credit do what it's built for: absorb the timing. In fat months, everything above the baseline goes against it and drops your average daily balance hard. In lean months, you draw living expenses back out. The line of credit becomes the shock absorber between when money arrives and when life bills you, which is precisely the job a line of credit does better than any other tool. A savings account can do this too, I'll grant that fully, it just does it while your buffer earns a little and your debt costs more, instead of your deposits canceling interest directly.
The danger is that the line of credit makes lean months painless, and painless lean months invite spending creep. If your baseline grows to match your good months, it stops absorbing timing and starts absorbing lifestyle, and the balance ratchets up instead of cycling down. That failure mode gets a full writeup in The Math Works Until Spending Creep Breaks It. Irregular earners should also hold a bigger untouched margin on the line of credit than salaried folks, for the season that runs long.
Getting a line of credit approved is its own project when you're self-employed. Lenders typically want two years of tax returns, and they underwrite off the income your accountant worked hard to shrink. Apply during a strong stretch, not during the drought when you need it. The line of credit you set up in good times is the one that carries you through the other kind.