It depends on your ticket type.
1. If you don't have a hopper pass, and went into a different park that day, then no, you cannot go.
2. If you don't have a hopper pass, but didn't go into any park that day, then yes, you can go to EMH, but it will waste a day for that short time.
3. If you have a hopper pass, then no problem going, and it won't waste a day if you were in another park that day, but will if you didn't go into any other park.
If your situation is #1, then your only choice is to upgrade to a hopper pass, or purchase a different single day ticket for $60 which definitely would not be worth it, IMO
If your situation is #2, then you can do it, but I think it is a waste of a day. Evening EMH in Epcot is not anything great. The lines are crazy for Soarin`....90 minute wait when I was there last time....pretty much 1/2 the 3 hours you will have. Test Track has long waits as well. The only thing we could walk into was Journey into your Imagination. The Counties are closed with the exception of Mexico and Norway. When we were there in May, you couldn't even walk around the promande, but I do understand that are opening America for EMH which means you will be able to walk at least 1/2 way around.
