Maximum Session is 9 hours

[lukepolo]

Reason being :
We use canvas and the number of seconds to determine where to play tick marks / activity markings on the progress bar. Canavs has a max width of : 32,767 for chrome / firefox.

https://www.tutorialspoint.com/Maximum-size-of-a-canvas-element-in-HTML

This is mostly a PHP side of things, and really shouldn't be a huge problem. Also we could somehow do things in terms of different units when it reaches 9+ hours.