Juggler and Double Trouble 2 are not very difficult in comparison to the other two bombs (I am Hardcore and Pick Up the Pace IV). Just remember to periodically check the needy modules and you should finish no problem. I finished with over 45 seconds remaining on both of those bombs. I am Hardcore is a little difficult, and I would recommend restarting until you get a "Vent Gas" module rather than a "Capacitor Discharge" module (since the latter frequently wastes a lot of time), but it should be no problem after that. I even managed to finish with over a minute left on that one.
However, the last one Pick Up the Pace IV, is pretty difficult and was the first bomb that really gave me trouble in this game. Because of that I will be going over that bomb in this solution. If you can get this bomb, you should be quick enough to easily get the other three bombs, even if it does take a couple tries to get a lucky bomb (not all bombs are created equal)
Pick Up the Pace IV:
I am almost certain that a "Wire Sequence" and "Complicated Wires" module will appear every time. For the two other modules, you will get two of three of the following modules: Button, Simple Wires, Keypad.
This one does require a bit of luck, since you only have 80 seconds (you actually have 80 seconds, unlike many other bombs where the timer speeds up and you have less time than it says; the timer does not speed up on this bomb) and one strike to complete all 4 modules. There are things you can remember and tricks you can do to help you finish fast, though. Here are some strategies I used.
First of all, I would scroll the manual to the page on the button, then right when the game finished loading, before the lights even turned on, I picked up the bomb and checked for a button. If one wasn't there, I would restart. If one was there, I would immediately press and hold. 70% of the time holding down the button is the correct thing to do. Look at the strip. If it is white, red, or any color OTHER THAN BLUE OR YELLOW
then immediately release the button. Bam, one module done and our time hasn't even started ticking yet. If it is yellow, wait until the timer reads 1:15 until releasing, and if it is blue, wait until the timer reads 1:14 until releasing. If the bomb explodes, that means that pressing and holding the button was a mistake in the first place and you just got unlucky, so you'll have to try again. I was able to get a good start like this around 40% of my attempts.
Another thing you can do is save the other module that is on the side with the timer until last. This way you know exactly how much time you have left while doing your last module and you know when you need to start guessing. So all in all, do the button first, then flip the bomb over and do all the modules there, then go back to the side with the timer and finish the last module(s).
There aren't really any good tricks for keypad modules, but they only take around 10 seconds total anyway, so it shouldn't be too much trouble.
With wire sequences, I memorized the first couple "rules" for cutting or not cutting wires. For example, you always cut the first black wire you see, the second black wire is cut if connected to A or C, and the first red wire is cut ONLY if connected to C. These were the only three I memorized, but you can feel free to memorize more if you think it will help you out. You will also need
to remember what occurrence of each wire color you are on, because there is no time to go back and check. I helped myself remember this by saying what number of each colored wire comes next every time I switched sections of wires. The manual's first column is for red wires, the second column is for blue wires, and the third column is for black wires. So for example, if the first section of wires on the bomb had one red and two black, I would say out loud "2, 1, 3" while the bomb was loading the next section of wires. This reminded me that I was on the second rule for red, the first rule for blue, and the third rule for black.
With regular wires, 75% of the time you are going to get 6 wires, and whenever you get 6 wires, if there is at least one yellow and one red, CUT THE FOURTH WIRE. This rule always works. Otherwise, you will need to check, but there is still a good chance that you will need to cut the fourth wire. If I was unsure, I personally didn't risk it since it only takes a couple seconds to check, but you may want to guess if you are low on time. (I would still recommend guessing the fourth wire, but you can also guess the 3rd or 6th wire) I also memorized that if there are three wires and no red, cut the second wire. This knowledge was good enough to get me through this module pretty speedily on most attempts.
With complex wires, WHITE MEANS NOTHING: a wire that is red with a star and no light should be treated the exact same as a wire that is red and white with a star and no light. Also remember that wires that look the same will always be treated the exact same. Combining these two rules can sometimes prove very effective in knocking out multiple wires with one check. For example, if you have one wire that is blue with a star, another wire that is blue with a star, and one wire that is blue and white with a star, you can knock out all three wires with one check. Also, be careful not to mix up the star and LED circles on the Venn Diagram, as they are both dots and looking from the key back to the diagram can be confusing. Fixing this really just requires experience, you will subconsciously learn the difference after solving enough of the complex wire modules. I did memorize a couple of rules here, too: An empty white wire is always cut, a starred white wire is always cut, but a LED'd white wire is NEVER cut. Lastly a wire with everything (blue, red, star, and LED) is never cut. These were the only four rules I memorized, everything else I had to check manually. I would also recommend looking for batteries when flipping the bomb so you don't have to go back and check. Remember that batteries can appear on any four sides of the bomb, so makes sure to check all of them!