If you're researching because you're thinking about risking a lot of money, then research everything. But if you just want to know which rice cooker to buy, open the first three search results in different tabs, read what you find, and ask yourself if you have enough information. You probably do, and are just suffering from personal indecision.

For more on this idea ("just enough" information), google "satisficing." For some things, I'd rather spend 5 minutes for 80% of the information than three hours for 90% of the information.