Modern motorcycle insurance policies already give you an automatic credit for winter layups based on your local climate. So there's no longer any need to go through the rigmarole of dropping and picking up your insurance each winter.
Dropping and insurance can also cause problems with your state's DMV (depends on the state -- most require that you maintain insurance, even if you swear on a stack of bibles you're not riding the bike) and with many companies, a period without coverage in your history can lead to much higher rates.
With all that said, Progressive is simply not the best option for many riders. My rate with Progressive spiked sky-high for absolutely no reason a few years back (I guess Flo needed a raise), so I switched to a different company. Dairyland had good rates for me, and has a good reputation. YMMV.
Anyway, don't drop your insurance -- it can cause problems. Do shop around -- there are better options than Progressive.
2002 Suzuki DL1000 V-Strom, Dark Metallic Space Blue
1983 Suzuki GS850G, Cosmic Blue
2005 KLR685, Aztec Red - Turd II.2, the ReReTurdening