If you consider each time as seperate from each other, without any relation, then the individual rate will remain the same. However, a basic knowledge of "Probability" will allow you to realise that the actual chance of getting it twice in a row will be lower
Lets use your Pinsir as an example.
Pinsir's chance will be 0.75% on the first day
On the second say, the rate that is in the game, will still be 0.75%.
However this is where it gets a little bit confusing
0.75% = 75/10000
(75/10000)^2 (Probabilty rule n^r) = 5625/100000000, or 0.005625% chance that it will occur twice in a row. That would technically be your 'actual chance' of seeing a Pinsir yet again.