Moving to 4-weekly from monthly will give you more work, not less.
One thing I regret years ago is going with a monthly schedule, I wish I’d done 6 weeks/12 weeks.
The problem with monthly is there aren’t the same number of working days in each month, so as you get full, shorter months cause you to get behind.
I used to be always behind by over £1k, then I took on an employee and within a month I was back on schedule and and am no longer behind, as well as being able to take on new work again.
If things get crazy again, I’m think I’m going to switch everyone to 6/12 weekly before I take on my next worker. Way easier to organise.