I don't think they need to do it indefinitely. The problem is just timing of transactions, like justice transactions. If the other side force closed the channel with an earlier state which favors them, you need to broadcast a justice transaction and this one needs to be mined fast enough (1-2 weeks) iirc what I read in Mastering the Lightning Network.

Not sure why @benthecarma said force txs. I thought it's about justice txs.

Or am I missing something?