I don't till except for the first time I prepare a bed, I topdress after that, simply wiggling a fork in my soil to loosen it but not turn it, and spreading the compost on top...
What happens when you do not disturb the fungal hyphae (long thin strands in the soil of beneficial or benign (for the most part) fungii that act as beams and girders holding the soil open (forest soils, which are highly fungal, are springy and airy because of this). This works in your garden bed as well, and soon you will wonder why you were busting your hump so much.
Repeated tilling breaks up fungal nets and powders the soil, eventually leading to compaction, which leads to anaerobic soil conditions so the bacteria and other animals in the soil die off, and the soil becomes less water retentive, less fertile, and less receptive to plant roots.
So topdressing and a little wiggle of the fork from here on in, and you will be amazed. Take care of your soil, and your soil takes care of your plants.