My last trip I knew my cell coverage would be too poor to stream but I was also running out of space on my phone, so I re-encoded my stuff to 360p, low ass bitrate.
It was a bit blocky for some fast paced action scenes. For sitcoms? Totally fine.

Is it worth 4 times the file size

For a TV or a Tablet, sure.
For a phone? Meh, unless you have a ginormous phone (mine is 6.67") I wouldn't bother