nolatom's comments sound like good advice for racing. If you're not racing, I would say that unless there is a major wind shift, staying on on tack is probably better since each tack will slow you down. Geometrically speaking, the total distance traveled by a boat doing that does one 90-degree tack is the same as one that does many 90-degree tacks.
There will of course be many other considerations. Sailing in narrow channels or channels with hazards will require more tacks, for one thing.
Current is the other big factor that plays a role as well. Sailing across the southern Strait of Georgia I'm often going nearly dead upstream against a current that might be 1 to 2 knots in parts. On one tack, I'll be going upstream and making a measly 1-3 knots speed over ground depending on conditions, while on the other tack I may be making 5-6 knots over ground but have negative VMG :P So I have no choice but to stay on the "slow" tack for most of the trip.
s/v Laelia - 1978 Pearson 365 ketch
s/v Essorant - 1972 Catalina 27