I wouldn't go as high as scaff boards anyway. I have raised beds. 2 types gravel boards and decking boards.
The problem with gravel boards is they are fairly thin, so once loaded with earth they can struggle to hold the weight, not initially but over time they start to warp out, and as soon as some rot sets in they will fail. Effective life probably around 4-5 years.
The decking ones as they are thicker seem to handle the weight better, whether they will last as long i cant say, mine are 2 years in and looking ok so far. The gravel boards I inherited second hand and found out when they were put up by previous plot owner.
The reason I say to avoid going too high is purely water. Raised beds are drier. So they do suit things such as garlic that are happier with, in fact prefer a bit drier later in the season. However things like beans are a bit more of a pain as they are water hungry and don't root that deep. Just means more frequent water required. Certainly the people near me at the allotment who grow at ground level do not need to water quite as much.
One advantage of the raised beds is they warm faster in the spring so you do get a benefit from that angle.