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A dozen of sites that I own consist of only a handful (1-5) of pages. The ones with relevant content are ranked, receive search traffic for their respective topics, and have gained TBPR (up to 5 to my surprise). Their performance has been steady and predictable for several months now.
The ones that serve only as doorways or are being used as placeholders for future content do not receive as much love from the big G.
The structure and content of a site is what counts. Once that checks out, overall traffic volume is likely to increase as the amount of relevant and unique content grows over time.
You should read Brett Tabke's seminal post on how to build a Successful Site in 12 Months with Google Alone (26 steps to 15k a day) [webmasterworld.com]. While the article was written in 2002, the overwhelming majority of points made are still valid today.