My experience is with oak adjuncts, and I got about the same results (oakiness) regardless of adjunct type, hence my comment. Specific flavorings do differ by oak type: when my son & I conducted our
Wine Stix experiment last year, the American oak produced fruitier flavors than the Hungarian, and definitely more than the French. Our month-by-month tasting notes are not exciting reading, but it may give you ideas. YMMV
That said, IMO your plan is a good one. As I'm fond of saying, it's easier to add more than to take some out. I suggest you stir the wine at each barrel topup. I use a drill mounted stirring rod and get the wine moving (no vortex). I've been stirring up the cubes and any fine lees to ensure the wine is homogenous before tasting (barrels manufactured 2010). I'm due for topup now and bottling next month, so I didn't stir last month nor will I this month, as I want the lees to settle. I pump to a Brute to homogenize the wine (whatever topup is left will be blended in) and ensure the K-meta is well distributed.
My barrels are long since neutral, and I'll be adding 4 oz medium toast Hungarian cubes to one with Grenache, and 5 oz to one with Tempranillo. I will also have a 23 liter carboy with Petite Sirah, Syrah, & Mourvedre -- I'm doing a 10 day EM on these grapes and the indication is a very heavy wine. I'll probably add 2 oz cubes to the carboy.
I add less cubes than some might, but the cubes will remain in the barrel/carboy for the duration, roughly 12 months.