Seems reasonable. The main reason for this wasn't so much disk space but just to reduce spam from the session. Since most connections occur more than 5 mins after the session starts, increasing the timeout won't impact that goal.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5c7b21cad070583a7cf21bdce54ca8bf64137208

commit 5c7b21cad070583a7cf21bdce54ca8bf64137208
Author: Lambros Lambrou <lambroslambrou@chromium.org>
Date: Tue Jul 17 20:30:06 2018

[remoting host] Increase X session logging timeout.

Only the first 30 seconds of the X11 session logs are kept. This
increases it to 5 minutes to capture more debugging output from the
session. For example, some session programs may be started more than
30s into the session (because of an X-GNOME-Autostart-Delay key or
the session is slow to start), and it can be helpful to see the
initial output from all startup programs.

Bug:  749215 
Change-Id: I12ba7ca252719e6fba36afcd8995049c29204ec3
Reviewed-on: https://chromium-review.googlesource.com/1103542
Commit-Queue: Lambros Lambrou <lambroslambrou@chromium.org>
Reviewed-by: Jamie Walch <jamiewalch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575757}
[modify] https://crrev.com/5c7b21cad070583a7cf21bdce54ca8bf64137208/remoting/host/linux/linux_me2me_host.py