Usually it is best to "oil out" a painting when there are some really sunken in areas, before any top coat of varnish or the like is applied.
I know it's too late to do that with this painting, though. I can't see any downside to applying more Galkyd Light. You may want to apply a thin, but full strength coat this time -- ie with no mineral spirits mixed in. That will give you more gloss.
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