Nope, that's experimentation. It's certainly not a waste! Gallon batches are good for experimentation -- if things go badly, you haven't lost much. OTOH, if things go really well ... you only have 5 bottles.
Use a bucket for primary fermentation. In addition to avoiding a mess, initial fermentation wants oxygen that it won't get in sealed container. When the SG gets below 1.010, rack it into a jug or carboy. While you only need a few inches of head space
most of the time, more head space is safer. I've had a few overly vigorous fermentations that made a mess in a bucket I thought large enough.
1118 will ferment a rock if given the chance. It's not a bad idea to keep a packet on hand if you're playing with other yeasts. It seems to be the go-to yeast for restarting stuck fermentation.