It’s good to do strength tests as you build, but it’s hard to know when and even harder to stop forward progress to make the time.
Well, the other day I tested the strength of the core hatch assembly. The hatch only has one layer of stripping, which has no strength until you put the second layer on. So… while moving the hatch to drill the port light openings I dropped it. The 80 pound hatch fell 5 feet onto concrete. BAM! Crack!!!
The damage: 4 strips popped their bond and cracked off the frame. All the separation was internal to the plywood.
The learning:
Don’t drop stuff.
Also, epoxy worked great. The damage was stress breakage. The epoxy was still holding 5mm of plywood to the framing elements under the broken stripping.

Fixing soon.