Maybe it depends on if the action is being danced on initial slow of the music, or on the consequent one. Generally you want it on a consequent slow, because the fundamental rhythm of tango is QQS aligned with the music, not SQQ.

A Tango walk is not danced as smooth and fluently as the walks in the other Standard Ballroom Dances where the time of a "Slow" is used to stay equally continous in motion.
In Tango we take full weigth on the foot at the first half of the Slow ( = 1st Quick) and NEARLY stop at the second half ( = 2nd Quick). I explain it like driving by a stop sign as a bad driver: you nearly stop but there remains a very littly speed (enough to get a fine from the police officer living at the crossroad only to watch you passing stop signs.)
So a count of "Stop" instead of "Slow" makes sense.
And we need some Stops more (perhaps someone will for that suggest another expression) for the figures where we have to stop on a Quick(e.g. step 3 of the Closed Promenade; step 2 of the Promenade Link ...)

"In Tango we take full weigth on the foot at the first half of the Slow ( = 1st Quick) and NEARLY stop at the second half ( = 2nd Quick)."

For both kinds of slows?

I shure hope you don't dance the first slow between a link and the closed promenade that way - though it might make sense to use this method with the second.

Actually, my mistake that's not an example of the musical variation in the slows, but an example of the what is coming next variation.

The slow at the beginning of the closed promenade needs to be executed more continuously, so that it can transition to a following quick which is an elegant, rather than awkward step through in promenade. That quick is then executed with the foot only moving with the body and not in advance as is usual in the rest of tango where the body might be relatively stationary during the early part of the foot movement. You need to drive right through that first slow and stop in between the quicks. In contrast, the second slow can physically be danced with a greater variety of timings, including the quick/stop one you propose.

Suggestion: the execution of the slow needs to change depending on the type of step that follows.

The reverse turn (lady outside) has another good example of a slow that needs to flow smoothly into the following quick to maintain an elegant hold.

Nobody has pointed out that on the ladies second to last step in the Reverse Turn( step five there is no further movement of that foot. It is placed with the toe pointing inwards, then close. To explaine a bit further. If this is Foxtrot as in a Feather Finish the foot on step five would move. The placement of that foot in Tango applies to any closed promenade. After a Link step 3 is the one to watch. Its clearly shown in the charts. The main difference between today and yesterday is the second to last step does not go down the LOD.but turns in slightly. The man also must turn to accommodate the ladies steps. Watch Marcus Hilton. There are of course exceptions to the rule depending what comes next.But for straight out Basics, finishes with the lady, backing diagonal to wall and not backing wall.