Maybe I've been "lucky", but I've gotten away with not leveling the frets on the last several I've made. No buzzing or anything. Well, there was one fret on one uke that didn't quite seat right which caused a bit of buzz at the previous fret, but I just fixed that one with a crowning file. Two caveats...these were sopranos, which probably makes a difference I think, and also I don't attempt super low action. 1/8 to 3/32 inch at the 12th is fine for me. And I pound them in, too. As they say, ymmv.
Now dressing the ends, you gotta do that, and it takes practice.
If you do want to level, it's not that big a deal, but you'll want to recrown the frets and need a good crowning file. I got the one from lmii that has three different size heads, and it's great for dressing ends round too.
Sorry, just noticed you said tenor..so maybe would require leveling...