Yeah I was going to say the same. Fungi species can grow real deep, large and invisible to our senses. I understand people ITT getting offended on throwing out food with parts rotten, but honestly if it's not an exception such as banana I will probably throw out the entire piece (like bread) if there is any part rot at all.
Bread is especially spongy, so I for sure throw that out the second it has a whiff of mold. More solid things like cheese though? mold doesn't seem to grow very deep on that.
Good point, yeah I should be clear that if like half my loaf of bread is moldy I'm chucking the whole thing; I'm only saving it if it's like a few slices at one end that are moldy. Probably would have been better to say that I cut off the part which is obviously good, leaving a healthy margin and tossing if in doubt.
White bread is actually super easy to colonize for mold, even a bit of mold is a near guarantee that the rest is moldy - just not with spores.
My tip is to only keep a half dozen or so slices fresh and freeze the rest. Frozen toast tastes just fine.