It might be too simplistic for you, but you can use the 'scale' command as described here: https://plantuml.com/commons#4252b72e6ebcd4d4. But I concede this doesn't achieve the same as having wider day columns would.
With last beta http://beta.plantuml.net/plantuml.jar you can have:
(you can click on the image)
It this what you are expecting ?
A new request...
Could you implement:
Labels on last column
Especially for Left to Right language... for better alignment...
We are not 100% satisfied by the syntax, but with last beta, you can have :
Regarding milestone, we are really out of inspiration about the syntax, so we welcome any suggestions!
Thanks for your help :-)
With this new feature:
you can add:
Projectscale daily zoom 2
and observe your expected result:
Thanks to PlantUML team for this new feature,Regards,Th.