About this spring thing...
If a leaf shutter is cocked, yes the springs are under greater tension, but more important is the fact that the unfired/cocked shutter linkages and release catches are now under more strain, most are pretty thin soft metals that are much more likely to distort/deform under tension and the more or less worn catches/locks (that release to transfer energy) are sitting with considerable tension/force at that (small) point or area... (Kind of like keeping an air rifle cocked... The spring does it's thing compressed inside, but we can hope that the rest of the components inside are not under too much more strain, so it makes sense to leave it un-cocked...)
The spring with the greatest tension is the cocking spring... This has some overtension so if the shutter has some resistance (from cold, lube issues, oxidation, etc), it still has considerable force to push everything along, but the timing mechanisms are fairly independent to allow the shutter to open and close at the right times, but being cocked, it is putting quite a bit of extra pressure/tension on the catches/locks...
The other big reason to keep the shutters un-cocked is that they are sitting at the best reset point at rest... The slow speed escarpment is fully at it's starting point (left set at the slowest speed, it is fully at it's full rest/reset position), the flat drive plates/linkages that drive the blades are not held back under tension (possibly distorting/wearing catches, etc), shutter cocking and release points are not holding back considerable force (like a mousetrap), and by the initial cocking, most all of the entire mechanism gets a little push, so there is a little exercise for everything and arms/slides/pivots move a little to break their at-rest seating etc...
If you dug through your old worst shutters, and had left one cocked in storage, you might release it only to find it releases (or not), but only partially opens, not opens, sluggish blade action, or barely or not close at all... Low speeds might be sticky due to the # of tiny pivots in the escarpment slightly sticking to their bearing seats before morning exercise, etc... But un-cocked at least most everything inside gets moved a little initially (during cocking), so somewhat a little less chance that is closer to a point it could seize or jam due to mechanical resistance...
Steve K
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