food stays in stomach for 60-120 minutes before slowly released in intestine, unless the sphincter at stomach exit is damaged. All that time there is full amount of acid in stomach. Most people with acid reflux have a poorly functioning valve at stomach entrance. That is why sleeping on left side helps. Because stomach entry is on right side.
At the end of day it all depends which part of stomach has issue, entry or exit. Eack person will need to find out for themseves.
Which makes sense and is easy to test. That, of course, and avoid lying down to sleep within 2 1/2 hours of a meal.