Speaking clearly is important all times. We accept that in business settings. We sometimes let our guard down, though, during private conversations. Of course, some of that is acceptable. After all, no one is perfect and no one expects perfection from others.
There is a fine line between casual and sloppy conversation. If you want to be–and remain–a polished speaker, you should practice the fundamentals in every instance. Some people think they can switch on the communication skills when needed (say, for a business presentation). That’s not as simple as it seems. Speaking clearly when necessary becomes easier when you commit to speaking clearly all the time.
Consider your phone or Skype calls, social gatherings, and other private events. Every time you open your mouth to say something, use the opportunity to practice what you’ve been taught. Eventually the principles become second nature, and you’re speaking well in all circumstances.