Affecting a bucketful of water is certainly Target: Individual (in the case it's not Part of some larger mass).
Affecting a bucketful of sand also seems Target: Individual. Would you instead argue that it's Target: Group, because each grain of sand counts as an Individual? What about gravel?
Affecting a bucketful of wool, however, is strongly implied to require Target: Group (by the Creo Animal guidelines in the core book) -- even though MoH:p.57, seems to assume it's Target: Individual. How do you play it?
What about affecting bucketful of grain -- Individual or Group? Olives? Apples?
Affecting a bucketful of vermin, such as spiders, seems definitely Group. However, I recally seeing somewhere a discussion about vermin being treated as an "uncountable", like water, and thus a bucketful of them would be Individual. Any clues on this?
Well, first of all there's quite a difference between a bucketful of something and a bucket of something -- in the former case you don't need the bucket! Second, Individual is obviously cheaper to use than Room or Group, and that's what really motivated the question. Finally, note that Room is unavailable for some types of magic -- e.g. if you want to use Creo magics to fill a bucket with stuff.
I'd argue in all cases that Individual is fine. What is needed is a Vessel or Container as a RDT, but it seems to be splitting hairs to not make it Ind and move onward with the story. Especially when the contents are very small, such as grains, etc.
If it was a bucket full of oranges, which are "fist sized" and could be visually targeted separately, then perhaps group applies. I'd argue that the magus could not target an individual grain of sand easily unless it was separated from the rest.
Always (always ALWAYS!) go with guidelines over individual spells.
Individual spells could be the (lucky?) results of experimentation or a creation of some not-fully hermetic maga. Take a look at Last Flight of the Phoenix if you need an example - but guidelines are the core, the bones and sinews we can base our systematic research upon.
