After you reach 72, each successful completion of the Digistruct Peak Gauntlet will allow you (once you save and quit) to raise the game’s level by one OP until you reach OP8. Each subsequent run through Digistruct is in theory harder, but depending on the spawns, the first 3 are roughly the same… As @Carlton_Slayer says, 72 gear will take you to OP4 at least, maybe 5. After that, not only is the level higher, but the spawns are much harder too and you’ll want new gear to reach OP8. I suggest a re-set and a quick run through of the Scarlett DLC and some Snowman runs, just enough to cover the basics as you’ll probably want to push to OP8 at that point.
You don’t have to re-set the level higher though, you can stay playing at 72 if you wish. In fact, you want to make sure you are comfortable with the character’s playstyle at 72 before going onwards. I pushed too fast with Krieg and had to back up to learn him better at 72 before using him at OP levels. Some people don’t even like OP levels and play at 72. Other people, like @Adabiviak, well ok probably only him, likes to use a wide variety of weapons and so prefers to play at OP3 (with OP3 gear).
Everything scales to you in UVHM, so if you are playing at OP2 let’s say, enemies will be at OP 2 (74), bosses will be two levels higher (76), and gear can drop on level, or at worst, two levels lower.
One annoying thing on console (probably the same on Steam, but dunno), however, is that in public forums it doesn’t show OP levels or if people are using OP gear. A person could be several OP levels higher with accompanying gear, and could join your game and just crush everything. I figured OP8 was the endgame and so I pushed thorugh to that relatively quickly with most chars, having a friend use the Gunzerker rocket jump cheese for my first few chars. In retrospect though, I wish I had done it legimiately with those, because it took me a lot longer at OP8 to learn how to play them at that difficulty level.
To finally answer your initial question, no I wouldn’t farm too hard at 72 if you plan on going to OP8.