You’ll probably want to add tisbe pods at least monthly. Check pod population at night with a flashlight. You’ll see them scurrying around the glass near the sand.
I’d suggest getting the mandarin used to you feeding it. Hatch live baby brine shrimp and use a turkey baster to blast them in front of the mandarin with all your pumps off. Once the mandarin is eating the live baby brine you can add cyclops and other frozen foods.
I’ve a mandarin for about 18 months and last time I added any pods was when I first set up the tank two years ago. It’s about 150 gallon total volume.
I think if you have an established medium sized tank it certainly can support a mandarin without constantly adding pods. If you have macro-algae in the sump it will make it that much easier for pods to reproduce and thrive.
I also don’t think that mandarins eating frozen or prepared food is very useful under normal circumstances. They seem to need to eat the entire day so feeding three or four times a day probably still isn’t enough for them to thrive.
Mine started eating frozen food after a few months of being in the tank and I used to love feeding it but I stopped doing it altogether and just let it hunt pods.