I didn't know shaking the paint bottle is essential I thought it's only required for the bottles like the Citedal ones where it get exposed to air.
Yes definitley essential with Vallejo. Just like the wife, much as I love her and them, I'm aware of their faults.
Vallejo Model tend to settle into Pigment and medium very easily/quickly, a good rattle for a minute or so and jobs a good to go.
Oh and what about Transparent (Clear) colors, why would someone need to use these? Are they for "glazing"?
Yes and No.
I use Vallejo transparent Red, Yellow, Orange and Green and for various tricks.
Red enhances a red paint without overpowering it, Yellow sparks green paint right up and really can put a "ooh" into a Gold metallic paint job as can Orange as a shading tone over a gold.
Green can take a so-so green paint job and just pull it back enough to recover and "make it right".
Having said all this I use these transparent colours so dilute, a case of touch the pallette with the bottle and then two to three brushloads of water. (real scientific measurement that you know) and work with a 000 brush most of the time.