People don’t realize that Konami isn’t ever releasing Synchros that require more than 3 materials like Flower Cardian Lightflare or Super Heavy Samurai Steam Train King
...Steam Train King only requires 3 Materials. (And it's even possible to Summon it with only a single monster on your own field thanks to Battleball.)
I'm not sure there even IS a non-Cardian monster that requires 4 or more Synchro Material.
And two of the monsters he used to summon 2 Synchro into the field with just 3 zones, are monsters we're sure to get: Quickdraw Synchron and Quillbolt Hedgehog, due to them being Yusei's often used cards