I will watch my females when i have a group and see if she is having trouble holding. I look at how large a female she is and has she held before? Is she being harassed alot by the others? Is she hidding all the time or out withe the others. What variant she is and any information that can help. If I know how long she held for someone else or know how long she held last time before she spit then that will give me an idea of when to strip. I have some that will go full term and others that will spit on day two. In general anything less then a day has been bad results with me and the longer the wait the less problems I have.
I have Kitubas which spawn somewhat frequently , but they are small spawns . The females will spit at times & this too is normal for this varriant.
I have gotten into the habbit , once I see a female holding, I stop feeding the tank for 10 days & throw a bed sheet on it. I have had no more spitting & the fish seem less stressed. Since this is a show tank in my family room, ther sheet realy helps.
Day 10 I strip & tumble. Hope this helps.