If they're going to stick in trading then that doesn't matter because non-competes are standard in the industry, so everyone will understand. Some take it as a way to get some paid downtime. A friend of mine, who joined my firm, went around Europe on his 4-month non-compete. Others do something like that, if it is too long then they just work in tech.

Some firms like Jane Street and Old Mission have no non-competes.