Is Heatshrink really Important?

I was just wondering how important it is to heatshrink the ends of your connections,  I did the big 3 under my hood and crimped 4ga and crimped 1/0ga, I'm looking for a bluepoint solder iron to solder them 100% secure, but they are installed right now only crimped and still remain clean looking, will heatshrinking benefit anything? should i wait until after i solder them solid? or is heatshrink and good crimp good enough?

What do you mean by

t0mmyr wrote: crimped 4ga and crimped 1/0ga

Did you crimp those together or are they at different spots?  And the point of heatshrink is to keep the bare part of the wire from touching something else that is metal.  It protects your wires from shorts. That's my opinion. Take it, leave it, or correct me.

they are on different spots, my alternator is on the left side of the motor and i have 2 seperate 4ga grounds, one from top block ground point to body, and one alternator ground point to different point of body, then on the right side of the motor i have 1/0 from the main battery ground point of the engine block going to negative battery, as well as the stock 4 guage is ran from negative battery to frame passed to engine block point, the positive 1/0 is run to a hole in a battery terminal on top of my battery, no crimped 1/0 + as of yet, it passes to an ANL fuse holder, actually all my wires into the battery are run through the battery posts w/ no o-ring crimps, i do have side posts on some stock aftermarket GM batt adapters i could heatshrink i guess if i can find some wide enough, other than that the battery is secure

Wait until you solder before heatshrinking.  In the meantime you could wrap with electrical tape if needed.  Tape can be unwrapped, heat shrink can't.Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.