I oil out my panels with a 1/2 stand oil-1/2 liquin (alkyd resin) mixture. I then paint into this layer of medium (Also called: 'painting into the soup'.) This has the effect that the paint flows onto the panel really well. The paint won't sink into the gesso layer here and there, preventing it from getting dryer in some spots. The film of paint will stay liquid all over the panel, so that it can be manipulated easily (ie. moved around with a dry brush).
I don't use mineral spirits in the medium. As these evaporate quickly, the consitency of the medium (and paint, painted into the medium) also changes quickly after having applied it. I like the consistency of the paint and medium to be constant as long as possible. Occasionally I do use a drop of mineral spirits on my palette, when I need a thin paint to draw a line or something.
When the layer of paint is not too thick (no impasto), this medium stays open for about 1 day. I can usually add the next layer after 1 day of drying. When I do want to apply thick paint (highlights) I use some impasto medium (thickened alkyd resin).