the answer is yes by default, by testing on a different system. Installing via GUI only closes down THAT session and has no effect on any other processes.
Likewise, installing toolboxes via the matlab installer (which doesn't require pointing to a license for sudo) does not seem to impact any currently-running instances of matlab/simulink.
I did not check whether sessions running during install have immediate access (possibly by adding a new path manually), or if the session has to be restarted/re-initialized for the license to allow use of the added toolbox.
