but everytime after a block took too longer to be mined then the upcoming 2 or more blocks will be mined in next few minutes
Time taken for a block to me mined does not affect the time for the next block which is in line. It's not a case where if a block takes too long before being confirmed the next one will take a short time, it's just about how fast miners can solve the puzzle.
Technically there is no relevance for the time take between each block should be like that but as far as I witnessed since I am using Bitcoin most of the times the network behaved in that way which is why I mentioned it.
Here is the example

After the block 797669 the next 4 blocks were mined in the time interval of 18 minutes especially the first 2 in the 3 minutes.