wouldn't it be easier to paint your p40 with gloss olive drab, apply your decals and then do a clear flat coat rather than apply flat olive drab followed by a coat of clear gloss, apply decals and then do a clear flat over that? It seems like an extra step, yet I can't seem to find a lot of the standard colors in gloss.
You are right. But then, you’d have to buy at least one less product which means less profit for the company selling you stuff.
Acrylics, even gloss, have a "rough" texture, which create problems for decals, Silvering (tiny bubbles).
FLAT acrylics, in fact all flat paints, have a rough texture, that’s what makes them flat, tiny bumps in the finish which diffuse the light, reducing reflectance. Gloss paint, whether enamel, oil, acrylic, laquer, or whatever, have exceedingly fine pigments and smoother carriers which reflect light better. Think of a mirror vs a woolen blanket.
Also, you need to "seal" acrylics against moisture from decaling.
Not so. Cured acrylic is as impervious to water and decal solvents as laquer or enamel.
So, I paint with acrylics, put on a gloss coat of straight future.
And that Future is what? ACRYLIC floor covering.
The only way you could save a step would be only if your don't do any weathering on your models.
True if the base p[aint is glossy, other wise you are very likely to get silvering.
Once the decals are on the model, another coat of gloss is needed to seal the decals and protect them from a wash.
Maybe. I have rarely used a gloss to seal the decals, going directly to a flat final layer before doing a wash.