"Richard" wrote...
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?

The guidelines you are looking for not only vary by class, but actually
by individual boat. How well you can tack is a large part of the
equation.

You are going to have to learn what the boat and crew can do and what
your local water typically throws at you.

All I know now is that the wind comes from the West about 300 days a
year and from the SSW about 40 days! But I have no clue about the
degree and frequency of shifts. That will be my mission for the next
few weeks.

Best thing would be to set out a couple buoys (or use some that are already
there) and do some trial runs. Tack between them using several techniques
(1 port/1 stbd; 1 stbd/1 port; 2 or 3 shorter tacks; tack on every header
of 10 or 20 deg, etc). Use each technique several times, recording the
wind direction/speed at the start and finish each time. If you can record
or note time to tack and speed lost in each tack, that might be helpful.

Repeat the exercise several times over several days, plot the results on a
spreadsheet or graph paper, and decide what works best for you, your boat,
and your crew. If you can't tell from the data, it probably doesn't matter
to a degree you can calculate, and maneuvering among other boats will have
as much or more effect on your times.