Best of the Best banner

I finally completed the Mass Effect challenge, (reward is the "Best of the Best" banner) a couple of days ago. Took me several years (!) of on and off play, though there was more focus the past few months to use weapons/kits I previously neglected. I never thought I'd actually get it, otherwise the effort/grind would have seemed so daunting from the onset it would have put me off from playing altogether.

Anyone else want to share their thoughts or experiences obtaining their BotB banner?

-- Edit 18 Jan 2016 --
Got my banner at around 500 hour mark. Last 100 hours or so were focused on finishing up partially complete challenges. You won't get BotB banner by simply playing as you please. A few people indicated it takes 2-300 hours to get it if you're reasonably focused, but that turns the game into a grind that you may or may not be able to tolerate.

While this BotB advice really comes too late for for ME3, perhaps some of it may be applicable to ME:A. Skim through all alien and weapon masteries - pick out weapons, powers and kits for 10 extraction challenges that seem interesting to try out. In other words, pick out challenges that seem fun/manageable first. Leave out the 200 wave challenges till the end, and by then many will be partially complete. Leave combat mastery over cover grab challenge till end - I repeated bronze waves 1-2/Cerberus/Vancouver for about half hour to get 100 or so remaining grabs. Solo mastery - bronze and silver can be done with pretty much any kit you like. Unless you like solo play, I don't suggest doing more than 1-2 attempts at a time. By the time you're ready for solo gold you'd know what kits work for you. For the 200 wave challenges don't force yourself to play with classes you dislike, even if it means trying and starting afresh with a different one, and not play on bronze simply to get it over with. Don't look at getting BotB as a race, because it's a fucking marathon that will eat you up and spit you out... I felt it was easier for me not to get hung up on the the really grindy (i.e. 200 wave) challenges even if it takes hundreds more hours.