Given the varying time it takes to mine 1 block, even as network congestion increases it will result in 2 to 3 times longer than the normal time.
This is completely wrong.
The time it takes for miners to find a block doesn't depend on how congested the network is. The average block time depends on the ratio of total hash power to difficulty and it's tried to maintain the average block time of10 minutes with difficulty adjustment every 2016 blocks.