I'll take the 30$ a year gamble of replacing 4 litres of atf myself, but that's just me...
my 2004 maxima, notorious for failing transmissions, started having hard shifts at 50 000km.
Started changing the atf every year(fixed it immediately). Sold it with 200 000km and a perfectly smooth transmission 6 years later.
The santa fe just started giving me rougher shifts after 2 years, and since I have changed the atf, it's been back to normal as far as I can tell, I didn't get rough shifts this week so far.
It's not really longer when you are already draining the engine oil to just pop another plug, let 4l out, measure, pour the same in, and done. Longest part is really just prepping, ramps, remove underbelly, and then the cleanup... oh well. whatever. trust me the fluid wasnt any shade of red....