Rich,
The last time I heard about someone covering the layout with a sheet, the idea was scrapped when the cat took to going underneath all the time!
You've significantly reduced the dust and dirt problem for sure, but even if it goes five years, cleaning the layout at some point will be unavoidable even though you covered it.
A lot of it depends on geographics, both of where you live and the location in the house.
By comparison with rural dwellers, urban dwellers are cursed with dirt. An article in a New York City paper some 20 years ago said that if you vacuumed and left the windows open for two hours, there would be the same dirt accumulation as if one had left the windows closed for two weeks!
The last layout we had was in a 5th floor bedroom directly in line with a power plant some three miles off. We loved having the windows open on nice days, but often we had tumbleweed muzzies blowing down the street in a good breeze! Though we're now in the sticks, we have yet again a coal burning power plant in line with the wind and us. The dust problem is not as severe, but it's not like being up north where it's clean!
Indoors, especially the basement without open windows, it can be still worse. This time the culprit is the furnace. Keep the layout away from the furnace room at all costs, preferably with a closeable door to keep the SOOT out. Soot and grime are the worst and get into the mechanisms to wreak havoc.
I've seen electronic equipment from environments where everyone was a smoker and that will destroy gear as well. Got any smokers around?
All that said, don't toss the vacuum yet!
George.
