Lava flowing faster than every 30 ticks when updated by piston

Lava should flow every 30 game ticks in the over world, but when I update it with a piston (like in a stone generator) it can flow more often. Setting up an 8 game tick clock (see screen shot bellow) and pulsing pistons to push stone out from underneath lava I see the lava flow down and replace the stone (my pistons are water logged) between every clock cycle, ie. the lava flows every 8 game ticks. I have not tested it with a faster clock as the pistons don’t work properly at a clock speed faster than 8 game ticks.

I first noticed this in 1.21.80, but it could have happened a few updates before. I know it was not the case for the first 1.21 versions.