Such was the promises for various companies offering trips with - to be fair - often more or less 'famous' climbers. I used to believe that such a promise was obvious hokum - I know my grade, and no matter what miracle workers went to work on me, improving even one grade would take significantly more than a week. Not that I've been on any such trips, but actually - such a promise, at least for a certain segment of the climbing populous in the UK is a very safe bet. Let's say that you're a typical UK weekend warrior of average talent and fitness. You have a full-time job, and you've climbed mainly trad for the last 10 years. You pootle along happily on HVSs in the Peak, and the odd mild E-grade in Pembroke or Cornwall, wind on your back. You climb down the local wall a couple of days a week. You've been bolt-clipping at Portland a few times, wobbling your way up the odd F6b, but also failed on easier ones. You understand intellectually that sport climbing is different from trad, but it feels strangely unsatisfying - cheating, almost - to rely on bolts. Also, you've heard that 'redpointing' means practicing, and you can't really see the point - if it's not onsight, it's a fail, and you move on. After failing on some F6a+ that you think you should have had, you pour scorn over the whole thing: "sport climbing is neither", and vow to spend the next bank holiday weekend at The Roaches instead, back on some proper grit HVS.
The big realisation for me was that to enjoy sport climbing you need to leave your trad mentality at home, with your trad rack. Sport climbing is all about the redpoint. If you sport climb to onsight, you're always climbing far below your level, and both missing the point and losing out, reaping no rewards. Sport climbing is about practicing the moves, to enable you to climb the hardest route you are physically able to do. This is very different from trad where the mental game is very, very different - placing gear where the rock allows, plus the uncertainty of its viability essentially adds up to a very conservative approach - nothing wrong with that, and essential experience for the all-round climber. However, with sport climbing, much (not all) of the risk element is removed. This isn't the same to say that sport climbing is reduced to a purely physical game - redpointing introduces its very own brand of mental frustrations. Top-roping to work out the moves before the lead attempt? Sure thing. Fudging your way up, bolt-to-bolt with a clip stick to rig up a rope? You bet. Trying the same route five times to fine-tune your sequence before finally sending it on lead? Absolutely. Attempting a F7a+ when you've only ever previously managed F6b? Well within reach.
Coming back to the coaching trip promise of grade gains - it's easy, if you've never really redpointed with intent before. You obviously won't become '3 grades better' - you will only have realised your potential by climbing properly at the right level. Suddenly, sport grades aren't barriers anymore, they're a measure of the time it takes you to do the routes. If you onsight at F6b regularly, you will almost certainly redpoint F7a within half a dozen attempts. If you stick with it, you'll notice a few interesting effects - as you start redpointing more routes above your onsight level, your on-sight grade will start to creep up much quicker than you'd dared to push it if you only ever climbed around that level - you're improving your skills. Also - your trad level and confidence will grow, as your fitness and technical skills suddenly jerks upwards. And you didn't need to go on a coaching trip either.