I'm asking a question about something i thought i understood - but now i'm not so sure.
Take foxtrot. Let's assume we dance 2 slows (slow, slow) using foot placements on beats 1 and 3. (please let's not get bogged down with 'steps aren't exactly on the beats', and 'steps start when the feet close' and so on, as i think this question doesn't require us to go there).
So how would you dance slow, &slow and how would you dance slow &quick.
On which beats (half beats included) would you make your foot placements?

Wihtout gettin too far bogged down, I'd point out that a foxtrot slow usually has the foot placement much closer to its second beat than it's first - the feet would really be landing more on 2 and 4 than on one and three.

Now in practical terms, my advice for handling a S-and timing would be the following: first dance it through a few times as two quicks, until you have all the actions and overall amount of available time secure. Now just shift the emphasis to give the first step more time than the second. What we are looking for here is an artistic feel, not mathematical precision.

Phil. One slow = two beats. Break the two beats into four half beats. Use three half beats to step and one half beat to bring the rear foot under the body and repeat if you wish.This is what you have been doing without realizing it all along. Once you have that sorted out there should be no trouble with the quicks. Simple explanation isn't it. Good Luck.