Don't Install Because the Release is Close
There is a very good chance that macOS Mojave will arrive alongside iOS 12 in September. With the final version available potentially within two or three weeks, you will be testing near final software, but also dealing with the hassles of installing the beta and then switching to the final version.
Even if you go through the trouble of making a spare partition to install it to, this is a lot of work for minimal payoff if you are a normal user. If you have yet to install the macOS Mojave beta on your Mac, it's a good idea to simply wait for the gold master or the final release at this stage.
We expect to see Apple announce the event date anytime now, and with loads of new Macs expected at the event a fast macOS Mojave release date is likely.