Author here. As always, I'm happy to take any feedback or answer any questions about this post.
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The biggest difference was that in 2022, I hired a paid ads consultant to set up ads automation for me on a few different platforms. That had a high up-front cost, but then it was inexpensive to maintain those ads in 2023.
I also spent money experimenting on more channels in 2022, so in 2023, I cut out spending on the ones that weren't earning a positive ROI.