Stochastically, fork can influence on block generation time?

I have known that we can calculate a network hashrate using ellipse time during 1 round(2016 blocks for adjusting difficulty)

Stochastically, we can calculate a contribution of all miner for one block.

For example, there are three miners and each miner have 50%, 30%, 20% of network hash rate. It means, during 1 round, stochastically each miner will generate 50%, 30%, 20% of 2016 blocks.

In point of 1 block, only 1 miner contribute 100% to generate a block.

But in point of 1 round, 3 miner contribute. for example, in 1 block, stochastically A, B, C miner would contribute about 50%, 30%, 20%

So i am curious that if fork is happened, generating block takes more time than before fork?

Let's assume fork is happened and one block is propagated to A, B and another block is propagated to C.

In point of 1 block, if A takes 10 min on average to generate block then A will take 10 min on average after fork too.

But in point of 1 round, A, B, C contribute together and it takes 10 min on average to generate 1 block.

However, after fork, A, B and C is mining different block and as a result network hash temporally decrease(because of split). so I think block generation will be delayed

Sorry my descrtiption is not clear.

But i am really confusing about it. In point of 1 block, block generation will not be delayed. but in point of 1 round, block generation will be delayed

which one is right?