IME, increasing pulse frequency can have an effect on increasing arc "stiffness", whether it be in AC or DC welding mode. (Arc stiffness increase = makes the arc more "directional", or more focused, concentrates the heat closer to the tip of the tungsten and not letting it spread out as wide, helps to penetrate more deeply and can sometimes allow better control of the heat.)

I think many people aren't aware that high frequency pulsing can have this effect in A/C welding mode, because most machines that allow high frequency pulsing (only inverter power sources are capable) will also allow adjusting the A/C frequency, which is generally the more preferred method of arc stiffness adjustment in A/C welding mode. (A/C balance is another common adjustment that can also affect arc stiffness as well, with more with EN% (more penetration and less cleaning) = more "focused" setting.

I may have one of the machines that could prove to be an "exception" however, in that it supports high frequency pulsing (up to 300Hz) even in A/C mode, while it does not allow adjustable A/C frequency (A/C frequency is fixed at 60Hz on my Mosfet-based inverter machine.) 300Hz pulsing can be of benefit in A/C mode to noticeably increase arc stiffness over not using pulsing at all. The main drawback I find to using this feature especially for welding thick aluminum is, I can't run the machine "flat out" with average amps = max 200 amp output capability, because for the pulsing to function effectively, the current needs to be reduced below the peak capability of the machine.