I've found growing shrooms to be pretty hit and miss when it comes to colonization by mycelium. I suspect it has to do with temperature. Brown rice flour and vermiculite cakes have worked fine for me, but sometimes the mycelium just doesn't take off. I can't remember ideal temp for colonization of mycelium, but I believe it's high, like upper 80's. If I was committed to growing some mushrooms and having failure, I'd eliminate every possible place error could hide. Use fresh syringes from a highly rated vendor, allow mycelium to colonize at ideal temperatures, do a large-ish batch of jars, 12-24.
Monotubs are a lot more work, but I had astounding success inoculating rye berries and adding them to a tub of pasteurized coconut coir, horse manure, and some other stuff. Cake are definitely much easier, though.