Is It Better To Keep Coins In 2x2 Flips Or In Books/Albums?

I just remembered something.

Great Aunt Tootsie used OLD Whitman folders which had the glue on the backs of the holes. After her NYC apartment was broken into [luckily the coins were not found] she stored them under a floorboard UNDER HER SINK.

[By old folders, The JEFFERSON folder had only the year 1938 printed. She hand wrote the dates one by one on the blank holes beginning with 1939.]

Well, imagine the consequences.

The folder on the bottom was the ROOSEVELT SERIES. They toned the most.
And, with some regret, I considered them a total loss. Though most were uncirculated as she picked them up as soon as they were issued.

The others suffered no apparent damage.

Each collector chooses the holders which make sense to him or her. No consensus is possible.

I use Dansco for the nice stuff. Plastic for the keys [TPG.]
2X2s for whatever I have that a decision is still to be made.
And a few are just loose or in tubes.