Cardinals don't need more water changes as other fish. Just keep the pH at 7,5 or lower for the long term.
Wild caught cardinals are much hardier as the farmed ones. It's just that almost all wholesalers switched to farmed ones in the 2010's once Indonesia sold them for less as they did in Brazil.
I have had Cardinal tetras for many years. They live about 8-10 years before I have to replenish. Nothing special, I change water once a week. My PH is 6.8 (I have CO2). IMO food is important. My fishes eat 60% frozen and live worms about once a week.
I've always read that cardinals are easier to keep than neon tetras. They thrive in more tropical warm water temps, where neons do better in cooler water.
I've seen that cardinals are happier at a higher temp & grow slightly larger than neons. Cards like upper 70s-low 80s; neons lower 70s. Neons are more mass produced than cardinals AFAIK but both are now I think.
Water changes are always good!! There's no reason not do them as much & as often as you are willing.
I've never seen cardinals for sale locally aside from one LFS that's long gone, although I'm sure you can get better ones through fish groups or mail order anyway.