I've heard so many opinions on this. Might as well get you guys'. If you're really sore from going to the gym the day, should you go the next day? As in, wake up the day after and really feel it, should you go that day? I've heard that your muscles need time to rest if they are really aching, but then I've heard that it also trains them if you go when they're sore.

I have that same problem sometimes, when I do lets say 4 hours straight of basketball 1 on 1 with only 2 water breaks.and then i get the same feeling after running 4 km and then doing weights

I NEVER train a muscle if its sore. Your muscles are rebuilding and working them out again while they are sore isn't only not necessary but bad for you.

Wait 48 hours before working the same muscles. If they are still sore that's ok. After a few weeks you'll hardly ever get sore anymore.

I train muscles once a week though you can definitely do it every 3 days. If you're still sore after 3 days and you've been lifting for a while, there might be something else going on.

I usually train in cycles of 3 or 4 days.
I've just heard so many opinions on this subject, from science teachers to guys who think they're professional lifters, with everybody contradicting each other.

I tend to disagree with this ideology ... Recovery time is good, yes, but if you work something 2 days in a row (or more), you can get much more out of the recoveries than you possibly could after 1 day. And yes, I have seen AMAZING results from doing so. I'm a very long distance runner (ie, races up to 100 miles), and when I'm training up for a really long race, the only way that I can possibly get into shape for a race like this is to continually overwork my legs with 15-25 mile runs every day for as much as a week straight without any easy days. By the end of the week, I'm just feeling it everywhere in my body and I don't even want to get out of bed, but a day or 2 later once I'm recovered, even a 40 or a 50 miler won't feel too bad. If I do this killer routine a couple times, I'm ready for the 100 miler. As far as lifting goes,
if you relift with sore muscles, you'll be able to make a lot more microtears and really punish them more. Once you recover, you'll be stronger than you were before.

Here's the dealio

Even if you AREN'T sore you there is a good chance you are recovering...so soreness is a pretty big red light.

Also, it depends on the intensity of your workout...soreness and pumps aren't a good indicator of htis