normally, shocking/cleaning is supposed to go on until 3 things all happen
1- loss of FC overnight is <1
2- CC is <.5
3- water is clear

If you meet 1 and 2, probably you can get away without more shocking and let the filter clear up the cloudiness, but no guarantees.
but to meet 1, you need to at least add the 3 gallons you were planning, test the FC after an hour with pump running, and test again in morning before sun affects the pool (earlier is better, sometime around sunrise or shortly after!) If that test shows 1 and 2 are good, just maintain it after that...
As long as the pool is maintaining some FC, it's safe to swim in- even at shock levels, its safe but maybe harsh on swimwear! just be careful, if cloudy, someone could "disappear" on the bottom and you wouldn't know it!