Extra Magic Hours "Gridlock"?

[Yusani]

"Extra Magic Hours At The Theme Parks
Disney World lodging guests are invited to enter a designated park 1 hour earlier than the general public each day or to enjoy a designated theme park for up to 2 hours after it closes to the general public in the evening. Extra Magic Hours can be valuable if you know how to use them. They can also land you in gridlock."
https://touringplans.com/walt-disney-world/resort-benefits

What exactly does that mean? How could I wrongly use extra magic hours?

 

[Robo]

We love AM EMH.

"Gridlock" seems like a wrong term to apply, but there can be some built-in "complexities" with EMH.

You really need to arrive a bit before the AM EMH park opens for EMH, (to be in a position to get into the park when it first opens... then you will get the full benefit of that extra hour.
If you straggle in during the last half-hour of AM EMH, the maximum benefit of AM EMH can be diminished.

After the first couple of hours that day, the AM EMH park might become extra busy as the morning gets later.
If it does, a guest with the hopper option can hop to another park or take an extended lunchtime break.

 

[Robo]

PM EMH's are a mixed bag. I've been when they were
"packed"... but on other nights (sometimes within the
same trip), the crowds were basically so low that it
was like "free rides" on all the open attractions.

The rule seems to be, it is far easier for guests to
STAY UP at the end of the day, than it is for them to
GET UP at the start of the day.

Generally speaking:
Expect a PM EMH which begins before 10PM to be much busier than one that begins much later.
Expect the first hour of PM EMH to be busier than the last hour.

Those who have attended PM EMH's and say that "they
are too crowded" are right... but that may have been only on the nights