That's kind of misleading, because it ignores the value of your labor. You work more hours, and you get a lifestyle improvement that can be measured in dollars. You're not preventing costs, you're changing how you pay.

If that's optimal in your specific case then great! But it's easy to imagine a person where it's not optimal at all. If Bob saves $X for every hour he spends on his house, and Bob makes $3X at his job, and he's equally happy doing either kind of labor, then Bob is a fool to do multi-hour household jobs himself.

Using time to save dollars is a tool, one that can be used or misused. You want to optimize lifestyle vs. effort, not lifestyle vs. nominal salary.

Over the long term you can either find some freelancing hours or get a job that offers a different expectation of worked hours and a different amount of pay.

So if you're out of balance you can fix it to do more of the job you want and have more leisure hours too. Or less of the job you don't want.

If I had a job where more hours directly translated into more money, 1. I would drop DIY projects and 2. I would probably become a workaholic.

But few have the talent.

And that skill usually comes from making mistakes and screwing stuff up on a previous job.

And very few people are willing and able to do the homework.