Yes, get rid of the air-gapped big can, but break down to whole gallons plus smaller pieces . Consume each gallon upon demand...in other words, open/decant and use one gallon at a time. First one breaks down to 3 quarts and then smalls (4 or 8 oz...12-16 oz if you build big and use a lot). Do the next one once you've used and broken down the first bunch.

I would do so with caution. I bought a gallon of Randolph clear butyrate a few years back with a friend. We split it 50:50. He found some paint cans at a store and decanted some into those. Whatever was on the inside of those cans discolored the dope. The original Randolph can is still clear. Maybe a really good paint shop could advise on suitable cans for lacquer. I wouldn't trust a big box store's cans...but you can always give it a try.

Dave