how to maintain a Betta tank with minimal effort

[Himal]

If you're testing params regularly and they're stable, you can adjust the water change schedule. Just keep an eye on nitrate levels. Above 20ppm is when you should intervene.

[Ryegrain]

Also, consider a pre-filter sponge on your intake. It'll catch debris and reduce how often you gotta clean the main filter. Low effort, big payoff.