Yes it is one of the best but 2 coats are recommended. Note that Altex no5 Plus is now out, claiming 2 years performance with 2 coats. Whitworths don't have it on their website as yet - at least when I looked the other day - but it is advertised in the August Afloat.

Looks good have ever used a diver to clean the bottom

2 coats and then a 3rd around water-line, leading edge of keel and the whole rudder for me.
I get 2yrs with Altex where i am, same with most of the locals as well. Done in late Sept, I'll dive on it maybe 3 times during the season (but never in winter, too cold for my bones, so just the waterline from the dinghy).
Talk to the locals where you sail, see what they use -conditions might be different.
We had a bloke move his boat down from years in Pittwater with a new coat of his regular AF, but within 8 or 9 months down here he was pretty badly fouled.

Don't know how to link this, so a pic.
Jode5 posted good reasoning behind the timing.

Yacht sea sun said..
Thanks ...I been told by the guys at the Marina that they only use one coat with a roller then one around the water line, Second one I went too is saying the same.
this seem strange when so far everyone is saying two coats and one more around the water line

That is fine if your slipping once a year. It's all dependent on paint thickness. Using the right roller and not going back over the work will give an adequate thickness. I slipped my commercial fishing vessel once a year for 24 years and it got one coat and a doubling up on the waterline and leading edges.
To get 2 years with a yacht and save on slipping costs and doing the painting yourself then go two coats. First coat a different colour so you can monitor how it lasts.

Good call thanks