At what point do you consider it worth the time to attempt to 3-mark a tank?

This is just a general question for the fine users of r/WorldofTanks .. The reasons most people try to 3-mark a tank are as follows (as I understand it):

• They really like that specific tank
• They are really good and like to 3-mark lots of different tanks
• It happened on accident (lol).

So let's say you like a tank. At what point do you consider it "worth it" to put the effort toward 3-marking it? After you've gotten 2 marks? After you've gotten a certain wr% in it? Because it's not a weekend anymore?

For context, I really like the M56 Scorpion. I've 2-marked it and I've even gotten as high as 91% MoE in it (without food). At this point would running cola and try-harding a bit probably net the 3rd MoE, or do I still need to git gud before it's worth the attempt? Consistency is hard, especially in a tank that has a hard time carrying games.