How many tuners should there be in a synchro deck?

In general, a Synchro Deck should run between 4-6 tuners, depending on the playstyle and focus of the deck. There are three types of tuners: Level 1, Level 2, and Level 3. Level 1 tuners are the most common and versatile, and most Synchro Decks will run 2 or 3 of these. Level 2 tuners can facilitate high level Synchro plays, but they usually require specific cards and combos. Level 3 tuners are often found in decks focused around using specific high-level Synchro monsters.

The exact number of tuners you should include in your Synchro Deck will depend on the specific strategy you are using. If your deck is focused on making powerful Synchro monsters early in the game, then you'll want to include a higher number of tuners. If you're playing a deck that focuses on Synchro plays later in the game, then you can get away with running fewer tuners.

Ultimately, the best way to figure out how many tuners you need in your Synchro Deck is to playtest it and see what works best for you.