I have been painting my Gauls for what seems like 20 years and I am still some way off completing them. Unlike their Roman counterparts (which can be painted in production line style) Gallic bases require a) different posed figures on each one b) different colour schemes for each one and c) non-matching clothing on each one (i.e. the trousers, tunic, footwear etc. are all different colours.
For this reason it takes me about 5x longer to do a base of Gauls than Romans or Spartans.
Then you realise that as Gauls are Gauls, you need a bazillion of them to meet your BG rota (1BG = 8 bases of 4 different foot clothed and equipped differently).
In the end I had to change processes to try and speed it up - but its still interminable.
And this is in 10mm! How people manage to do 28mm Gauls or similar is beyond me - they must have the patience of saints.
This also leads to Gallic-aversion. They look at me in their half-finished state as I pick up a lolly stick with a few Imperial Romans on it. Drybrush the chainmail, bit of red trim and leather trim, flesh on the face and arms, gunmetal the sword and paint the shield red. Job done. So much more appealing to actually complete a BG in an evening rather than get to finish painting the tunics of half as many Gauls. So they get left aside again and again as more attractive options are chosen.
A similar army are the Parthians with their multi-coloured horse archers (and you've got to paint the horses as well!). One day I will have to knuckle down and get them done - but I bet my Roman army will be completed well before then!
I want to give them a go, really I do. I've completed nearly all my heavy foot, my skirmishers and some chariots. But there's still loads of medium foot and all the cavalry still to do.....will it never end!!??!!