I just check the Path schedule and yes , you are right. Thanks so much to provide this information
"Newark - World Trade Center:
Operates all times.
Saturdays & Sundays: Terminates at Journal Square. Transfer to Journal Square - 33 Street (via Hoboken) train for service to New York. No service to/from Exchange Place or World Trade Center."
My husband prefer to go in May when weather is warm, but I found out no express deal after May 8, and before April 30-May 5, it is $250+ per night. I was thinking dates before Memorial days should be good and can get some deal. Am I wrong?