These problems are not math -- they are just guessing games. Given any sequence of numbers, there are always different logical patterns that produce the sequence.
Spend as much or as little time as you want looking for patterns in these sequences, knowing that any answer you find for any of them might not be the "right" answer.
On a quick glance at these, many of them seem to be sequences formed by splicing two sequences. For example...
I: 90,10,85,15,80,... can be written this way:
90, 85, 80,
10, 15, ...
Then it APPEARS that the next number in the sequence will be 20... but there is no way to know if that is the "right" answer.
And, by the way, your post says to find the "missing" numbers. There are no missing numbers in any of these sequences; so I assume you meant that we are to find the NEXT number(s) in each sequence.