Are early Dragons Worth it?

Okay so I'm trying to learn jungle. I've been playing as Vi because well her ganks seem easier to me than Jarvan's and she's tanky and at my wood 5 MMR rating, no one ever goes tanky so just having a tanky champ usually means my team wins. Like my last game where there was a super fed Yi and I went tanky Cassiopeia we ended up winning because thornmail OP against Yi.

One of the things I try to always do is solo dragon at level 4 after my first back at level three getting usually my jungle upgrade, and then picking up level 4 off of wolves or wraiths or last buff.

I've been watching a lot of jungle videos on Youtube though and it seems like they never solo dragon even if they have a good chance to. Such as like enemy Jungler being top, and your bot lane is pushing hard and the enemy Mid is visible. I sweep and check for wards but its rare that mid or bot or enemy jungler have the time or money to have wards for it at level 4 anyway.

Anyway, when they do comment about it they usually say that 6% extra AD and AP isn't really worth it early game, is that true? I mean 6% isnt that much but it's gotta help your team with last hitting and poking.

Basically I'm just wondering if I should use my first one or two chilling smites to get early dragon or try for a gank. Any help would be appreciated. If all three lanes are holding their own, would you rather your jungler farm, add pressure by forcing a flash/summoner, or solo dragon?

(Also I'm only talking about junglers with easy escapes soloing dragon. I'm not going to tell the entire enemy team where I am with the dragon swirly alert unless I can Q out of there on Vi.)