Uni is so much better than full-time work. Sorry if that's depressing, but it's true.
I like how you're proving its better by saying theres something even more shit around the bend. 
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Theres no real way to cheat them seeing your grades. They do all matter but in the end, it is up to the dude hiring you, they might not even care about grades all that much. They're not some robot, they're a human who will take into account other factors aside from your grades. 
Theres another reason as well, for some degrees, third year is really when you get down to the actual nuts and bolts. I did no pharmacology units in first year (all really general stuff "biology" "chemistry", etc), a single, very introductory one in second year and now only in 3rd year am i doing 4. So, if i was applying for a job heavily related to pharmacology or especially honours (or pharmacology masters) my 3rd year pharmacology marks would concern them much more than anything i did in first year and certainly if i failed 1st year french or something. 
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ou need to pack everything you want to do into the week and somehow make it all fit together. If there's on piece of life advice I will give you guys it's this, get off the facebook and casual posting on forums and start fitting everything you want to do into your life. I guarantee you in your later years of uni you will regret not using your free time more effectively. 
Oh God, this. Definitely. 
Only in third year (aka now) did i actually do things at uni. I live pretty far away and its quite hard to fit in but i managed to fit in some sports at uni and i'm loving it, despite the time sacrifice. It's just like the advice i give out to year 12s on this forum, it isn't all work, try to make it at least enjoyable or not super intense. You only get one life afterall. 
That said, everyone has different goals, different wants and defines waste in different ways. So, people will have different opinions and they can all be right, because its really up to the individual what counts as a "waste" or a "goal" or a good use of time. 
Reminds me of a quote (which is plastered up on my wall) "A man who dares to waste one hour of time has not discovered the value of life" - Charles Darwin
This is the wrong attitude. Uni gets much much harder as it goes on. 
I don't know about *much* harder but theres less babying and everything else, its all very direct and you're expected to be on the ball (this is true for uni in general but by 3rd year even more so).