example: chance of finding a product : 50%
4 jobs of each 30mins, with 10% bonus over 50% = 4 x (50+5) = 220
1 job of 2 hours with 10% bonus over (4x50%) = 200 + 20 = 220.
Its all the same really.
The only difference you theoretically have is with luck-items (no products). In every job you can get a maximum of 1 luck item so :
- With a 2 hour job you can get 1 luck-item;
- With 4 jobs of 30mins each on every job the chance of a luck-item is 1/4th of the chance of getting a luck-item on a 2-hour job but in theory you could get 4 luck-items in 2 hours since you're doing 4 jobs.
Even better, in 2 hours you could theoretically find 12 luck-items if you do 12 jobs of 10 minutes each........
when dealing with probabilities, you should take care that they don't add up, but rather influence themselves in a progressive way.
that is if you have one event with 50% probability, if you do 2 times you will not have 100% probability. You will only have 75% probability. And if you wanna feel better about it, you will never ever ever have 100% probabilities, no matter how many times you try.
For mathematical reason, the probability P to have an event E with p probability after n tries is:
P = 1 - (1-p)^n,
where ^n means raising at power n
that means you can have event E happen 1, 2, 3 or more times, but the probability to have it happen at least once is the above one.
for your case, 2 hours means 4 intervals, you have:
P = 1 - (1-0.5)^4 = 87.5%
and we assumed that you don't let your motivation get low since the motivation diminishes your chances to get the product.