In our parish council, apologies are noted but not approved and the minutes clearly state this. This is because in the past councillors have not turned up, not apologised and then once in a blue moon, sent apologies and these were approved; therefore resetting the 6 month clock.
In order to deal with this, as the council was effectively working with less councillors than it should, a resolution was made to not accept any apologies. In a harsh world, you could argue that if someone had a long term illness that prevented them from attending one single meeting in six months, then they should be resigning for the sake of their recovery and for the benefit of the council.