Daniel45:
I am old enough to have known many people who survived the Holocaust. This subject was discussed several times. There were not these huge pilgrimages. People did visit kevarim, but it was occasional, and usually involved the chassidim who were local plus family who may not have lived in the area. The productions we see today did not even exist then on a smaller scale.
The Remah’s yahrtzeit is on Lag Baomer, and there was a rather sizable pilgrimage to Krakow for his yahrtziet. It also became a locality where there were many weddings, often well over a hundred that spanned from the night of Lag Baomer, again in the morning hours, afternoon, and again before nightfall. I heard this from people who lived in Galicia. But this was exceptional, probably a substitute for Meron, which was then a huge distance to travel.