A few possibilities on time period of ANH--
--Yes, we don't know how long the droids wandered in the desert. For that matter, we don't know how long they rode in the Sandcrawler, do we?
How far is the drive to Mos Eisley? That could have been a good part of a day, maybe.
As to the question of how long it took to get to Alderaan; if you really look at the scene it seems to only take a very very short amount of time. (All in one scene) Han comes in from the cockpit saying "Well, you can forget your troubles with those Imperial slugs, I told you I'd outrun them." This possibly implies that this is his first time out of the cockpit since the hyperspace jump. Now, here is where it gets confusing--he then says something about arriving at 0200 hours. What he should be saying is they will be arriving in about TWO minutes! Because the training scene plays straight through for only a couple of minutes before he he says "Looks like we're coming up on Alderaan."
Another possibility of a time jump (very nitpicky, I know) is how long are they on the Death Star? I know the action seems to be very straight forward, but how long did they walk around in all those corridors getting to the elevator and then after the trash compactor? The Death Star is pretty big. When was the last time you were in a really big mall or a huge airport? It can take forever sometimes to get from one end to the other. Like I said, very nitpicky, maybe disregard that one.
Again, we don't know how long it took to get to Yavin IV.
How long did it take the rebels to analyze the plans? Jen told them about the "fuse", right? But surely they had to do some detective work to figure out exactly what to do.
And last but not least, and maybe the most important possible time jump is one I've not heard anyone talk about yet. How long from the time of the Yavin IV battle to the award ceremony? Surely everyone had to be debriefed, clean up, get some rest, get their uniforms pressed, etc before it took place. I will admit I don't know much about the military, maybe some of you military guys and chime in here. How often does a ceremony with that much pomp and circumstance actually take place on the day of the battle? It could have been the next day, or a few days or even weeks before the ceremony took place. We just don't know.