PerroneFord:
Doing 6 days a week, twice a day of what kind of diving? Is there ripping current? Is there a tough shore entry? Are they diving off a RIB? Drift dives? How about diving in cold conditions? Low vis?
Part of diving experience to be an instructor is having VARIED experiences. When someone shows up at this resort from Boston, and wants to get certified, and starts asking questions about drysuits, and thermoclines, is someone who has done all their diving in the Phillipines going to be qualified to answer? When someone from the pacific northwest asks about shore entries, is the instructor going to be able to give a credible answer?
Everyone is new at some point to teaching if they do it. I was at one point as well. But in a sport where a failure can be lethal, I want an instructor who has a bit of experience under their belt. And I don't care if you do 1000 dives in 6 months, it's just not the same.
I wish the original poster all the luck in the world. There are hundreds of instructors out there who've done the same thing. But I honestly don't think it's the best way to go.
DING, DING! You win! I was hoping someone would bring this up.
Sure you can pound out 300 dives in six months in idealic conditions. But what happens when he has his instructor cert, moves back to the UK and now has conditions that warrant dry suit, limited vis, nasty shore entry, rocking boat entry?
How often do you think he will face entering off the boat with 2' swells but have to get back on the boat in 12-15' swells wher the boat prop and ladder on a 65' boat are clearing the water by 4-6'? I've done that diving oil rigs in the Gulf of Mexico. (Provided a great deal of chum for the fish also).
How about doing Search & Recovery for drowned children?
River diving? Diving in <1' vis at night? Same conditions in 40 degree water? Diving in <1' vis with large creatures that you only get glimpses of fins?
Getting tangled in fishing rigging at 130'+, exceeding NDL and giving your dive computer (and wife) a nervous tick? Spending 2+ hours decompressing in the water?
Dodging jet ski jerks that think your dive marker is a turn buoy for their race?
Getting snagged by Joe Bob or his cousin/brother/dad that thinks he just hooked the local bar record Channel Cat?
Being in 4-5' vis at 60', have a 90lb female student choke, freak and decide that if she tears out your regulator, eyes and testicles, gets a death grip on her power infaltor, these things will get her safely to the surface? Maintain control of her until your other DM arrives to control her, then get your reg, eyes, mask and tesicles back, don't drown yourself and NOT kill her?
Slip on the icy rocks while geared (kitted) up on a shore dive at a high altitude (9,800' above sea level) lake?
Watch a 180 day wonder instructor use the down line you set in the morning, lead his students as they all CRAWL (instructor included) to 90' for their deep dive, then CRAWL (instructor included) back up, surface, go to shore and start debriefing, THEN realize they are short one student? He joined our group by mistake, but never went back to that instructor.
Just a few examples.
Sorry, but these 90 & 180 day "wonder" instructor mills scare the crap out of me. I've seen too many of their product and it's not pretty.
My recommendation is to dive varied conditions, seasons, climates, locales. Get more experience under more conditions than just ideal or nearly ideal.
Personally, I had 15 years and over 2,700 dives before I beacame an instructor. I still have more to learn than I have years to learn it.