Lizardmen could've been done in 2 episodes, 3 if you include the whole Ice Roach part. 5, or was it 6? was an absolutely stupid choice on the director's part. They have to understand that anime =! light novel. You can't just skim over boring parts and focus on important plot points.

You can totally skip adapting unimportant parts and focus on exciting action scenes instead and have a great adaptation.

All the readers who keep complaining about missing details in the adaptations of their favorite works should watch Overlord (and last parts of UBW) so they understand what the alternative is.