Usually it's not a generally safe idea to look for templates by a $URLSegment value in it, as it's far too dynamic - especially when you're giving the site to a client who could change page names, interrupting the $URLSegment value.
And, AFAIK, there's currently no way to set in stone the page URLSegment value. A good reason to not is it's generally good SEO to make sure it's updated to reflect the content / title of the page.
Again it depends on what application you're using SilverStripe for. If it's for yourself, no problem I guess. ;-)