I kept seeing more contests on Facebook and Twitter that required people to share a post. I found them irritating and stopped running them for my own internet projects. My original article quoted Facebook's rules at the time and said sharing for entry was forbidden. Platform rules change; that text is not a current legal guide.
Reach is not interest
A prize can persuade people to spread your brand name. Yet reach among people interested only in the prize says little about future customers or trust. When timelines fill with similar offers, another shared post may annoy rather than attract. Do not measure only how often something is shared; ask whether the right people understand your product and want to return.
Consider the friends of participants too. A voluntary recommendation means something different from a post required for a chance to win. People are more willing to share a good idea or useful article because it adds value.
Design with care
If you run a contest, state who can enter, what they may win and how you select the winner. Check current platform terms and applicable rules before publishing. My lesson from the old share-to-enter contests is not that every promotion is wrong. Brief distribution cannot replace an offer people want to discuss of their own accord.