"Internal switch. The voltage at this pin switches between (+VIN - VSAT) and approximately -0.5V with a duty cycle of approximately VOUT/VIN. To
minimize coupling to sensitive circuitry, the PCB copper area connected to this pin should be minimized."
..yes, it is the "switching node"...it has massive relevance in EMC as it can fail you on EMC. The switching node should be made as small in area as possible. I must admit sometimes i violate this when i desperately need it for heetsinking.........but i violate it and feel the fear.
Attached is my SMPS PCB layout doc.
(The switching node bangs up and down in voltage with very high dv/dt, and causes radiated emissions and capacitive emissions, which are a nightmare for your EMC test....keep it small......it is a devil within your SMPS..it is evil)
You need to have some area to it...but if you can shield this with "quiet node" (eg ground or power rail) copper then its a bit better...ie kind of hide the switching node behind the quiet node copper