Planning what order to do stuff in is a vital, yet very difficult, part of software development. Agile wisdom usually stresses the need to do things in order of “business value”, but this can sometimes be extremely tricky to evaluate.
Another approach is to do things in an order intended to decrease risk, such as starting with the most worrying, or least understood parts of a system.
While this sounds plausible, I am not sure I entirely agree the reasoning. Behind the idea of ordering things by risk seems to be the idea that there is some bounded set of requirements, known early enough in the process to be able to determine their “worry”. To me the whole point of agile development is to step outside that assumption into the real world where work needs to start before full scope is defined, where priorities change on a whim, and development on a product may be cancelled at any time.
Starting work by spending a few iterations investigating complex/risky parts of some imagined future product instead of delivering usable but minimal versions from the first iteration seems somewhat irresponsible.