What is the best way to paint TAU armour?

[Parfs]

So far all the better painted models of Tau army I have seen seem not to shade the painting but to just run a fine outline around the armour, this does give it quite an impactful look. Granted some have used weathered effects but still using the outline method.
What you guys have told me about shadings and watering down and layering seems not apply to the Tau armour? Maybe my eyes are failing me (that would probably explain my poor painting skills ) or they are just really poor picture quality. Overall some of what I think are good examples of Tau use this outline method.
What do you guys and gals think?

Here are some examples of what I mean from CMON
https://www.coolminiornot.com/154011
https://www.coolminiornot.com/152513
https://www.coolminiornot.com/150944
https://www.coolminiornot.com/149203
https://www.coolminiornot.com/148285
https://www.coolminiornot.com/147142
https://www.coolminiornot.com/145689

[Trovarion]

Well, just because there's a lot of examples out there where people only paint edges of tau armor that doesnt imply that a logic principle of miniature painting (zenital lighting, or shading respectively) doesn't apply to painting Tau armor.

mind you everyone has a different taste and might be satisfied with just edge highlighting, which is perfectly fine.

[hnoor0077]

What you guys have told me about shadings and watering down and layering seems not apply to the Tau armour?????