It's hard to say how much compound gets used when polishing because it rather depends on how many times you need to go forwards and backwards between compound and papers (often you find there are still scratches and need to go back to the papers again!). In really broad terms, which I think is all it's realistic to come up with, I would say that for a one-off project, even a large one like polishing a whole resin-coated table, then the smallest 100g packs would be sufficient. This would apply to both types of compound (NW1 and the TOPFINISH2).
If you're using compounds regularly, for example if you're making resin products as a business, then you would have either the 500g or 1kg packs in stock and work your way through them over a period of months, replacing when necessary. Certainly a 500g pack of NW1 would be more than enough compound for lots (maybe 10+) river tables, for example.