it is common to fly slower than cruise speed
In altitude True airspeed and turn radius are greater than it seems showing IAS. That is the biggest danger when the ceiling decreases blocking the path and doing the valley smaler. Temptation gets great to increase the bank. If you have low visibility you see the obstacle later and you want to finish the turn. And engine has less power too. That is the typical mountain crash.
But hammerhead must be masterized and well trained. Bubbers44 who is aerobatics instructor is better than I to developp.