Well the stabilizer is quite good, actually it should be bossible to shoot 1/2 sec or so but I can't. 1/5 is the lower border no matter what focal length.

oh ok, I thought about my Sigma lenses, which they don't have optical steady shot system and it's hard to get a steady shot with such long time, but my Sony lenses have and with these is much simpler.

Oh, there is e.g. Sony A6500/A6600 with body stabilization, but I use A6400 which is mostly the same but with no stabilization inside.