Where did the Clinton presidential campaign overemphasise and neglect in 2016?

Question

I’ve heard claims that the Clinton campaign neglected either the Midwest or the “Rust Belt” in 2016, allowing Trump to win the presidential race even though Clinton won the plurality of votes.

Assuming that electioneering is a zero sum game, neglecting the Midwest means that they paid too much attention to other places. Maybe they were trying to win states they didn’t have a chance of winning, or were defending states that weren’t at risk of being lost, or assumed the battleground states were somewhere other than the Midwest, or were trying to help with congressional races.

Where did the Clinton presidential campaign neglect, and where did they pay too much attention, if the aim was to win the presidential race?

Basing answers on information only available after the election is fine, because I don’t know what information was available to the Clinton campaign during the race.

Answer 1

In 2016 republicans held more campaign events than the democrats. According to this data,

+--------------+------------+-----------+
| States       | R Events   | D Events  |
+--------------+------------+-----------+
| Pennsylvania | 28         | 26        |
+--------------+------------+-----------+
| Ohio         | 30         | 18        |
+--------------+------------+-----------+
| Michigan     | 14         | 8         |
+--------------+------------+-----------+
| Iowa         | 14         | 7         |
+--------------+------------+-----------+
| Wisconsin    | 9          | 5         |
+--------------+------------+-----------+
| Minnesota    | 2          | 0         |
+--------------+------------+-----------+

The clear trend is that Republicans held more events by a wide margin in almost every midwestern states. In Pennsylvania they are a bit closer. So, data actually suggests Clinton campaigned "neglected" midwest.

However, nationwide they also campaigned less than their counterparts. Only in Florida they held 36 events compared to Trump's 35. Except that every states had more republican events than democrats.