Walmart has quit carrying Duco. I heard from a possibly reliable source that Duco's manufacturer quit selling to Walmart because they used it as a loss leader, to the detriment of other retailers.
As for clamping time, I take the clamp off after maybe 5 minutes. Just open the clamp and tip it sideways so any glue sticking to it will break the bond without stressing the feather joint.
I find Walmart's substitute glue to be too thin, way slower to dry and smells like cheap perfume.
I'll find Duco if I have to buy it from Amazon as mentioned above.
Jim Davis