We've gone through different phases of financial tracking.
When we needed to turn on a desk-top computer to input stuff into a spreadsheet, we found it to be too hard to maintain beyond a month or two, and writing things on paper on the fridge to add to the spreadsheet later didn't work so well. But we maintained it for long enough to get a handle on what we spend and how, and to set our 'normal' to something that works.
For years now we've just been keeping an eye on the balances to make sure they're trending in the right direction. If something looks odd, we'll look more closely at the month's statements. Oh, and we buy very little with cash - aside from a few standing weekly payments (like DH's sports subs and our straight-from-the-farmer milk purchase) it's all via our joint credit card or our joint bank account, so that makes it easier to track.
We have an agreement to discuss any purchase over about $200, and we both have very similar values and spending patterns so neither of us takes advantage by making stupid $190 purchases on the regular, for instance.
Just recently I've downloaded a spending tracker app for my phone (MoneyWise), and I really like it. It's not supported on multiple devices, so I just get DH to tell me when he spends cash, and ask him for details of anything that comes up on the bank accounts that I don't know about.
I'm still working out how to get the most out of it, but the biggest plus is the ability to update everything on the fly (don't need internet access to add transactions), and I love the way it just magically makes graphs for me :)