If it's peeling, it's really time to mask of the section, scrape back the peeling part and re-varnish. It should not get to the point of peeling before maintenance happens
While it's still looking lovely, maintenance coats should be going onto exterior varnish, like clockwork. I'm told by very experienced folks with lots of brightwork (and professionals who do it for a living) that in the tropics you need to set a schedule and put a coat or two on every 6 to 8 weeks, religiously. When in higher latitudes, once at the beginning of the season and once at the end will usually do a great job of maintaining a good varnish job. The "good varnish job" has about 8 to 12 coats on it before "maintenance" can start.
I'm still getting build coats onto several things, but our caprails and covering boards have been on "maintenace" for a year now and sunny San Diego has me doing this every 8 weeks. The only real problems I have is that I've got a hard interface between chainplates and varnish where the chainplates penetrate the covering boards thus there is cracking of the varnish just recently. I will be putting a 3/8" perimeter of Tremco sealant (a flexible sealant) around each chainplate to fix this little problem.
If you try to isolate the varnish from hard things that don't expand/contract with the wood--like chainplates, fasteners, etc, and if you keep up with a maintenance schedule for your part of the world, you should be able to keep a good quality varnish on your brightwork without stripping for anything from 6 years to 12 years. The maintenance coats are key--as is the process of inspecting the varnish and dealing with small scratches or hard spots (over a fastener, for example) as soon as they become a problem.
N--That product seems similar to Le Tonkinois. We use classic Le Tonkinois
for the bright finished edges of cockpit seats and anywhere else that abrasion or foot traffic will be heavy (one of the interior companionway ladders is finished with this as it is also a little less slick than varnish). One might wish to use this version of Le Tonkinois
but I haven't tried it.
The product is not as long lasting as varnish--it must be touched up more often but is much easier to add coats and less finicky about temperature, sun/shade/moisture etc. It is not as clear as varnish though. Because we have both varnish and Le Tonkinois on mahogany on the exterior of the boat, we can see the small differences between the two.
95% of what we've got in the way of trim is varnished--on teak, fir, and mahogany. Works fine and is hard to get all those initial coats on but is easy to keep up once you've done so. The rest is Le Tonkinois or painted. If you choose to paint, lay on a couple coats of vanish first so that you can take the wood back to bright easily at some later point.