when you are assigned to catch a number of dirty bubbles:

• you can collect the easy ones
• die
• the number of bubbles collected will stay, but the bubbles will reset
• repeat

i don't know if this saves time, thoughts?

i don't think the die strategy works on ds, i've tried it. it works on psp though

Can confirm that it doesnt work on DS.

However on DS we can bus/enter to somewhere and bus/enter area back and the bubbles count will be the same. But when you die it goes back to original.