Richard wrote:
It looks like I'll be sailing in Catalina 27's and 250's for the next
year.

I've been reading a lot about:
Tiny boat: Take every wind shift.
Huge boat: Not always! With the time/distance lost in turning a large
boat this may not be best.

So what would be the general rule for 25-27 footers?

What rules/guidelines do I use to learn properly the best way or
frequency or wind shift arc to tack?

It depends entirely on how much you like to tack! If you're racing you
would want to take advantage of every real shift, perhaps tacking every
few minutes. If you're daysailing with "no particular place to go" what
does it matter? A properly executed tack has very little loss; if you
have to explain which way to wrap the winch it might not be worth it.

I often sailed my Nonsuch 30 like it was a dinghy, tacking on every
shift, and often beating faster boats upwind because it was easy to sail
efficiently. I tack my catamaran much less frequently, and generally
power rather than tack out of a harbor.

FWIW, if you're going a distance upwind and you're always on the wrong
side of 5 degree headers, you could end up sailing 15% further. If,
however, you just ignore the 5 degree shifts, you'll perhaps be giving
up about 7-8%, or about 5 minutes on every hour.

Or, you could just adopt the motto "Gentlemen don't sail to windward."