Normal Zana Bosses need to be grindable way faster

Not only one cannot target farm the specific boss (you get the 80% less likely option which can still fail) but it barely spawns and they are another 4-6 maps to get.
Not to mention that once you start a thread, you are blocked till you complete it.
It's such a hit n miss mechanic that it's quite annoying frankly.
It needs to be map fragment itemized similar to the other bosses.