Most analytics screens are built around what is easy to count. That is not the same as what is worth knowing, and the gap between the two is why so many teams check their numbers every week and still cannot say whether the last three months went well.
Start by separating reach from impressions, because they answer different questions and are routinely used as if they were interchangeable. Impressions count how many times something was shown. Reach counts how many people it was shown to. A high impression count with flat reach means the same audience is seeing you repeatedly, which is a fine outcome for a campaign and a warning sign for growth.
Engagement rate is worth tracking only once you have decided what to divide by. The same post can be reported as a 2% or a 12% engagement rate depending on whether the denominator is followers, reach or impressions, and all three are defensible. Pick one, write down which one, and never compare a number calculated one way against a number calculated another. Most disagreements about whether a post did well are actually disagreements about the denominator.
Follower count is the number everyone quotes and the one that tells you least about the current month. It moves slowly, it lags everything else, and it is trivially inflated. Watch the direction over a quarter if you like, but do not use it to judge a campaign that ran two weeks ago.
Resist comparing the same metric across platforms as though it means the same thing. A view is a different event on each network, saves and shares are weighted differently by each algorithm, and a good rate on one platform can be an ordinary rate on another. Compare a platform against its own history, not against its neighbour.
The most useful discipline is to choose three numbers and hold them for a full quarter. Changing what you measure every month guarantees you never see a trend, because you keep resetting the baseline. Three numbers, unchanged for three months, will tell you more than a dashboard with thirty.
One caveat worth knowing about any tool, including this one: when you connect an account, its existing followers arrive with it. That arrival is not growth, it is the starting line. Judge the months after the connection, not the step that created it.