WRONG WRONG. I do agree that:
See about hot loops. In a boost converter, the output capacitor is part of the hot loop. In a buck converter, the input capacitor is part of the hot loop. There are other important points as well such as gate drive paths. For any low voltage (<50V at least) switching converter, stray inductance is the problem more than anything else, and that the datasheet is usually the best guide for using a given chip.
I like to use track widths which are wide. Generally I use 1 mm tracks for current < 50 mA but of course these need to be narrower in many situations. Copper zones are your friend.
Use generous ground planes. Most switcher IC datasheets will include layout information which illustrates partitioning IC quiet analog ground from noisy power ground. Doing this is often not necessary if your current is not too high, but doing it is better than not doing it and wishing that you had.
EDIT:
Jim Williams is a long revered expert in the world of analog circuit design. But the components have advanced so much since 1987 that I think that much this app note is out of date. Examples of this are many uF of small low ESL inexpensive capacitance in SMT ceramic capacitors, much higher switching frequencies, lower inductance in all sorts of SMT components, lower ESR in polymer capacitors which I think were completely unavailable then. Also a quick scan of the app note showed me no layout examples. Good pcb layout is critical and Ninja_kg0 is correct to be focused on this.