Should we create a database structure with a minimum number of tables?

Should it be designed in a way that everything stays in one place or is it okay to have more tables?

Will it in anyway affect anything? 

I am asking this question because a friend of mine modified some database structure in mediaWiki. In the end, instead of 20 tables he was using only 8, and it took him 8 months to do that (it was his college assignment).

EDIT

I am concluding the answer as: size of the tables does NOT matter, until the case is exceptional; in which case the denormalization may help.

Thanks to everyone for the answers.

IGNORE the number of tables. Worry more about getting the design correct. If your major concern is quantity of tables, you should probably not be designing database systems.

If your friend only needed 8 tables, and the system works fine with that, then 8 is the correct number, and the remaining 12 might not have been necessary for whatever he was doing.

Possible exceptions might be peculiar environments that have hard limits on table numbers, but I can't think of a concrete example of such a system off the top of my head.
