The 'quicks' are hops on the L,R.L foot. This SSQQQ description does not seem to fit into 6 counts until you realize that the first 'quick' is the last half of the second 'slow', as described below.
Here's an expanded description of the Shag basic:
Count Weight Syllable Description
1 left kick/tap/hold gesture with right footThere's also an open position like Charleston, Lead's right hand around Follow's waist, outside hands waving around like flags, or joined at waist height when closing, both partners facing the same direction, the direction of travel. In the open position, you can do the same basic, but now that you're in the open position you have the option of traveling!2 right step put right foot down
3 right kick/tap/hold gesture with left foot
4 left step put left foot down
5 right step hop on right foot
6 left step hop on left foot
There are two traveling varieties, depending on traffic avoidance considerations: slow and fast. Fast traveling is a step forward on 1,3,5,6 and slow traveling is stepping forward only on 1,3. This is hard to describe correctly with text.
Here's a comparison between shag and 6-count swing:
Count Weight Action Weight Action
Shag 6-count
1 left kick left step2 right step left hold
3 right kick right step
4 left step right hold
5 right step left rock back
6 left step right rock forward