FFMPEG – pull 10 frames every 10%

ffmpeg -i file -c:v libwebp -vf 'fps=1/".($Duration/10)."'-vsync vfr img%01d.webp

I first find out the duration of the video, then specify how many seconds it is necessary to snatch the frame.

The question is, is it possible to do the same without first calculating how many seconds to snatch frames???