XYZ and Bealzebub are spot on. I used to think that much of the ATPL stuff was irrelevant but more and more I appreciate the grounding it gives in the operational knowledge you need to display good airmanship and judgement.
It is always heartening to know that when the situation arises you have some store of knowledge about JAR OPS requirements, ATC regulations, performance requirements, flight planning and fuel policy as these things can often crop up.
I'm not saying I know all this stuff and religiously read my Oxford notes every day - most of it is in the company ops manuals anyway - but occasionally a situation will occur which causes something to stir in some dormant recess of my mind and I will remember some little scrap of information from ATPL exam days that proves useful.
Learn in order to pass the exams, but try to retain some of the vital info such as those mentioned above. It will serve you well one day.