You can really fastly paint Epic infantery this way:
- undercoat black or grey
- dry brush and basically paint faces, guns etc...
- wash the whole mini with dark wash/liquid pigments (Citadel washes/Onyx Woodland Scenic tips/
Michael Kan Liquitex Payne's Grey), you can even drop the whole stand in wash

- once the wash is heavily placed, blow (with your mouth or with a "hair dryer"?)from the top of the mini to make the wash flows downside the mini, to get less wash on the top of the mini and more at bottom (just like if the ligh is coming from the top of the mini). The wash will darkly shade all deep details of the minis and will act as a filter on the drybrushed details, it will hide the dirty effect of drybrush.
- let the wash dry (may take few hours) and highlight some details like guns etc...
As the Army Painter Shades are basically wood varnishes, keep in mind that you'll never probably be able to strip the minis once it's dry. On my side, I use WS liquid pigments and dilute them with a mix of Pebeo mat acrylic medium and few drop of alcohol.