Generally speaking, using a FULL year's history of cash receipts and disbursements will be a satisfactory basis for projecting the future.
Step-by-step explanation:
Though a rough projection can be made in half year's data as well, but a good and solid projection can be made using full year's data. Almost all business run for a full year, so its good to project on an yearly basis. Like in this particular year the profits are this much, so we can project that in the next year we can see a higher profit.