Some may be spontaneous, but most are pretty well planned. 90% of them, you never hear about. For instance, did anyone report the Trump Boat Parade AND a Trump Caravan today in San Diego?
Trump Caravan, Boat Parade Take Over San Diego 2 Days Before Election
The organic enthusiasm for Trump is far larger than reported. If elections were decided by crowd size, Trump would win in a landslide. But they are decided by votes, so everyone needs to drag every person they can to the polls so we can translate this enthusiasm into 4 more years.