It's true the series goes from having unbelievable highs to face palming lows (luckily more of the former) and I would say even since the beginning of the future arc it became more and more about random power ups and less about strategy. Not that that was a bad thing (because the different flame types and TYLisms brought a new element that made the series exciting) but around about Choice I to was begging to hark back to the Varia arc.
On the subject of Reborn fights, one of the reasons I feel this series works for a wide range of people is because all the guardians bring a different fighting style/weapon unlike say Bleach where it’s all sword. For example where I'm guessing you prefer strategy over turf tops or baseball idiots = Gokudera, I like nothing better than an over the top martial arts match = Ryohei (sometimes Hibari if I'm feeling generous), so the series caters for all needs. Of course this doesn’t mean we don't enjoy the other fights and in fact I was really looking forwards to Goku vs Shitt.P but it ended way too quickly and out of nowhere which I guess you can at least say was original. Incidentally the length of recent fights have been all over the place. Even the super-hyped Hibari vs Adelheid seemed to lose steam once Hibari did what he always does :(
I still maintain high hopes for Tsuna vs Enma though, but anyway sorry for the extremely long post. Oh also I just checked and if you count pre-fight taunting (which I always factor in :D) Yamamoto vs Squalo was six chapters long with plenty of is he dead yet moments :)