Pat I have an HP-CS and call me overly careful, but if I'm not going to be using the AB for a few hours then it gets a full strip down and clean. As far as I'm concerned if you've finished spraying for a couple of hours that's the end of your session.
As to what my cleaning procedures are for a color change, well depending on the paint (enamel or acrylic) I will fill the paint cup with a small amount of White Spirits or Windex and was the paint residue around with a soft brush, I then dispose of the White Spirits or Windex in an old jar. Next I swab out the paint cup with a cotton bud (cue tip) to clear any fluid that’s left over, and then I spray a small amount of the appropriate thinner through the AB to prime it for the next color.
Happy modeling