Once I bought a kit and it contaminated on me, so yeah it isn't even a guarantee for the rather lazy among us.
Aside from that, it can be a chore but if you are of the researching variety it can also be fun in the meanwhile. The thing is, you just have to keep it interesting for yourself so always check what kinds of things are possible and what's ahead. Growing shrooms totally isn't gonna work if you are only interested in crops, you have to be curious about the whole process & theory etc IMO.
@Fagott: you can perpetuate a culture, sure. It is just that once every so often you have to actually mate your fungi so that they can diversify genetically, otherwise they will degenerate and show what is called senescence (they become a geriatric form of fungus which sucks ass). To do this you have to go through the reproduction stage of producing fruiting bodies (reproductive organs), spores and the stage where genetics combine. After that the fungus is more like an individualized differentiated organism, which has weaknesses and sickness, genetic errors and perhaps shrinking teleomers all of that piles up and you gotta wipe the slate clean and start over again.
Keeping a culture in the fridge puts it in stasis, but still the proper thing to do is to get a piece of agressively enthousiastic fungus and propagate it, then select the best sectors in petri dishes and repeat a few times. That allows you to isolate a monoculture, not sure if that is most analogous to just breeding or even eugenetic engineering... but that will really give you great stuff.
At any point of the perpetuation of the master culture I just described you can take pieces off and turn them into spawn so that is definitely a yes.
Just remember that like I said earlier, you wouldn't only be "multiplying" the same culture, that culture will turn into other cultures in future generations. It has to keep evolving, recombinining. You can stretch a bit with cloning though.
