Is there a better way to nest if blocks in google spreadsheets ?

Yes. Use the SWITCH function. Here is an example using your code:

=SWITCH(H4
1, "CORRECT",
2, "CORRECT",
3, "CORRECT",
4, "CORRECT",
"Incorrect")

The last entry is the default, if H4 does not = 1, 2, 3, or 4 then the last entry is the result.

It is very similar to the standard programming function called SELECT CASE.