This is the most important, it's so much better for obvious and less obvious reasons.
I tried to print a front basket in one piece for my wife's bike 2 times before I got it to print. It broke the next week. I changed it from 1 part to 5 and joined them with zip-ties, thread and 3d-printed pins. Despite the assembly time I was finished in less than half the time, every part was stronger because it was in best orientation, the linkages had some give to them which provides surprising amount of amortization that wasn't there when everything was in one piece. It shakes the contents much less on uneven road because the linkage to the bike is only rigid one-way. It also prevents parts breaking easily, and if something breaks I just have to reprint the weakest sacrificial part that joins the bike with the basket.
And if I think of an improvement - I just need to reprint small part instead of everything.
BTW another very useful trick is preventing layer splitting by designing a vertical through-hole into which you put a zip-tie in tension. Some people use bolts and nuts for that, but that's more expansive and much heavier solution.