About 9 years ago I worked in Thailand for a year. I thought it would be a good opportunity to finally replace my late eighties Bic Hard Rock and rig of unknown manufacturer. I got a good deal and ended up with two new boards and four sails, type NP V8 - 6, 7 and 9 sqm and a NP SuperNova - 5,5 sqm. (The SuperNova will not be mentioned again as it probably is the worst sail ever made)
The first time I tried the new gear, rigged the 7 m, and followed the instructions exactly. Had no fun at all. I could not get speed I expected, I was thrown off all the time and were utterly exhausted in less than an hour. The whole session ended up with me calling a friend to collect me a few kilometres down the coast, I could not sail high enough to get back to where I started.
This episode made me realise a few things – a work out every now and then during off season does not hurt, a 7 year sailing break makes you lose some of your touch and of course; it takes time to learn your new equipment.
My trick was to buy apply some stationeries: A ruler, a pen and a small notebook. After every session, I measured the distance between the mast foot and the sail, the outhaul, boom location, harness straps location and length and mast foot placement. In addition I noted conditions, especially wind and waves. Finally, I wrote down how I felt these settings worked and ideas to be tried out next time. Although it made me feel “geeky”, it worked. During that season I learned how to optimise the trim of my gear to fit my sailing style and current conditions.
Nothing wrong with manufacturers recommendation – its a good starting point, but they does not tell you in what wind and wave conditions they will work, nor are they adapted to your preferred boom height, board type, style of sailing, etc.
I guess my recommendation is to listen to your peers, but make up your own mind as you gain experience.