Several people have told me it's not. Several people have said on the forums that it's impossible to top out without grinding big xp quests as support for the argument that quest repetition should be separate between epic and heroic (I don't care, separate them, current system, both work fine but own up to it's a choice to grind out quests in heroic, not a need!). So I decided to see.
With the exception of four quests that I did repeats on (Tempest spine because it's just FUN, TOR grinding out scales, Running with Devils to help a guildie, and Mindsunder trying to get a few goodies) I leveled Tortoise to 20 on an elite once and done path. Maintained an elite streak til 19, then dropped to hard for quests no one wanted to run and I couldn't do elite on my own. The only grinding I allowed myself was slayers, where the quest pickings were slim. I forgot some quests entirely along the way, and skipped the Titan raid pack entirely (I'm add, I'm surprised I didn't skip more!). I did no level banking, leveled up as soon as I hit enough xp and got out of the party so I didn't harm anyone else if leveling was a problem.
It's slower than people who grind the big xp quests, sure. But it IS possible. I'm not bragging, or suggesting others should do it my way, I'm just saying it's possible, and it was a lot more fun to me than grinding the same quests over and over. I got a wide variety of loot and a huge block of favor, somewhere around 3800 despite the ones I missed and will have to do just for favor. I didn't even get to Amrath before I hit 20. This post is for all the people who told me I don' t know what I'm talking about when I said it could be done, and that I needed to shut up telling people otherwise. You were wrong, and I will continue to not shut up. : ) I don't get mad, I prove my point.
Benefits: Aside from favor and fun, I haven't done any other than the four I listed more than once, So I have PLENTY of quests to grind for epic destiny favor. It is a choice to level faster by grinding wizking, delera's, shadow crypt, etc. etc., not a necessity. I had a blast, and will continue to not sweat quest grinding. So many people on my server that I met along the way were curious if it could be done, I thought I'd share the level plan in general instead of Sarlona.