it totally depends....
how long does it take to get dirty?
I store mine outside in a grass and gravel field so it pretty much stays dirty unfortunately.... As it is, I'd like to wash it maybe 4-5 times per year but can't find the time often...so in reality I hit the roof roughly 1-2x a year, and do a wash of some level maybe 3x. I'd want to do more if we used it more often....
The other variable is if a lot of bugs are splatted form the trip.
keeping it indoors, & if I had nothing but lots of time available, and assuming I used it a lot...I'd think I'd do a cursory wash after any trip with lots of bugs or otherwise got filthy...say from driving in rain
and I'd do a more thorough wash maybe 2x per year... cleaning the roof and doing a bit of detailing and waxing...
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