When I was in grad school I simply had savings targets and as long as I was meeting them I did not worry too much. Maybe I could have done better with tracking expenses but I'm not going to beat myself up over it now. I switched to tracking in Mint in 2012 (around the time I finished school). If you have shared finances, tracking is really helpful for figuring out where your money is going (not in the sense of blaming one or the other person for "bad" spending, just because it's the best way for both of you to get the information).
In 2014-2015 we noticed a bit of an uptick in our monthly spending. Some of it we could explain with rent increases, but this past year we also identified a few other more "discretionary" areas that we thought could use a little tweaking. Result is that in 2016 we have some shared and individual goals for reducing expenses further.
One thing I think tracking is useful for in our case is that our income IS a lot larger than our expenses, so just having "savings targets" without any sort of expense tracking doesn't necessarily force us to be aggressive--we can easily max out 401ks and IRAs and add quite a chunk of change to non-retirement funds without thinking much about it (last year our savings rate was over 75%, with very little active effort to curb spending on our parts). However, reviewing our finances reveals that we are definitely sometimes making sub-optimal spending choices--not so much in the sense that we buy luxurious things, but that we sometimes buy luxurious things that don't really make us any happier or healthier. For me, a big reveal of our tracking has been that I eat out during the week a LOT more than I would have thought. A good chunk of this eating out occurs during stressful weeks at work--I wouldn't have really thought of myself as a stress eater, but it turns out I am. Just knowing that helps a lot when it's 2pm and I don't want to deal with our buggy model and am thinking I might just run over to the drugstore for a snack--money aside, I now KNOW what I am doing is a response to stress and that it's not good for me (I'm not saying that always makes me stop doing it, but it definitely serves as a deterrent at times). This year I decided we should set a monthly "food" (grocery + dining out) budget and for January at least, it's definitely kept me from engaging in that particular self-destructive behavior, because I don't want to blow the food budget and let down my husband.
We've also found it useful for being able to go back and review "big" expenditures if we are thinking of repeating them. For example, we last did international travel in 2013. We have a vague idea of how much we spent but it's nice to be able to pull out the data and use it as a reference point for planning some international travel this year (our big takeaway is that we paid way too much for flights and need to get better about accumulating points/miles cheaply). In 2015, we moved, something we had also done in 2013. The move was a similar distance and volume of stuff so it was nice to see what we had spent previously and be able to use that as a starting point for figuring out the likely cost of the move, though this time my husband got to run the show of packing the U-Haul and the result was that we actually did is somewhat more cheaply this time!
So, TL;DR, tracking can be quite useful for a variety of reasons. If your method of tracking is fairly mindless/low-time investment (e.g. Mint or YNAB), I'd continue, just for the sake of having the data if you want it in the future.
