Not a fair comparison. In common parlance, there are no other uses for "w/" than "with". Certainly "4" usually means 4.

(Edit: Turns out that if 80 is the limit, "for" would've fit. Hah.

    $ len "Show HN: Encourage children to use the net more for learning with Pihole 5beta"
    Length of 'Show HN: Encourage children to use the net more for learning with Pihole 5beta' is 78

... I also would've left out "more" because... am I really wanting to encourage my kids to be on the net more than they are already?! ...

Perhaps something like "Show HN: Shape your kids online time with PiHole 5Beta"... but anyway cool project. It does shape things like Khan Academy as punishment / work, though. Like... If you only give your kids broccoli, they'll like broccoli. If you give them candy, then say "you can only have more candy after you eat 5 bites of broccoli", they'll f'ing hate broccoli and covet candy as their new god. But the real world is messy like that, eh? :-D )

For me, it is. I spend most of my day staring at code and I think that's caused me to have a strong cognitive switch between numbers and letters, at least with spaces around them.