Going through tutorial videos, I see people using the Real Time Preview and not having this issue. Not sure what could be causing it.
Every so often, the Real Time Preview window in the browser stops working and says
"Save all the files (including related files) to preview."
Is there some setting that I have not checked that will make it stop having to manually save all the time in order to keep the Real Time Preview functioning ?
Real time preview is hit and miss .... I would change the setting to 'default to static browser preview' in edit >preferences > real-time preview then just manually refresh the browser ... I've had more success using LiveReload along with the Firefox plugin
RTP is a nice feature in theory, but in execution, it's flawed.
That flakeyness that Paul mentions, in concert with the fact that it requires a connection to Adobe's servers in order to function, stops me from trying to get it to work anymore.
Switching to Static Preview, what the old Preview in Browser has been renamed to, allows me to keep my work on my machine and not need to rely on Adobe's server up-time in order to do my work.
To answer your question, no. Saving often is necessary for RTP to work.
I 2nd Paul's and Jon's sentiments. Real-Time Preview doesn't play nice with my local testing server, so I don't use it. I use Open in Browser instead. Save changes often with Ctrl/Cmd + S and refresh browser.
When I need to test on other devices, I use my local server's IP address which replaces any need for Device Preview on Adobe's servers.