On MSX1, this is always 50/60hz. On other MSX generations we can reduce the frame rate by 2, 3 or 4 using bitmap table switching. Typically this is used for scrolling.
We can switch at same time the character/pattern generator table and character/pattern color table in screen mode less than 5 but I think it is rarely used. In general, it skips frames only to manage the music, keyboard, calculations, sprites display but the image remains displayed at 50/60 Hz. Anyway it can only be divided by 2 to 4 otherwise it would be too slow or variable, ie awful. Dividing by 4 is a bit too slow for an action game.
I do not mean what is the frame rate of vdp screen redraw.
I mean: the game does a lot of vdp copy operations, for moving sprites and for scrolling background. How much of those operations you get while miving sprites and scrolling background in an interval of 1 sec?