Laidlaw, 75, said he never planned on seeking another term on council past this year.
"The reason is, essentially, because there is never enough time to concentrate on the council's core business- the environmental, conservation, and resource management issues, which are what attracted me to regional council in the first place."
It was more demanding to be a councillor than ever before with regional councils being asked to do more and more, Laidlaw said.
He pointed to the new Natural Resources Plan as one of the things he was most proud of from his time on council.
"It's a very thorough blueprint for environmental integrity in this region."
The bus network was "part of the picture" behind his exit but he was comfortable about the timing, Laidlaw said.
"I've put a lot of time into this along with other members of the council into making sure that we're on the right road to getting the bus service up to scratch for everyone and I'm very confident that will happen now."
But current council deputy chairwoman and sustainable transport committee chairwoman Barbara Donaldson said she wanted to see those improvements through to the end.
"It's true we had a bad start but it is improving. We're now looking route by route at what changes we can make without disrupting the whole network so that's continuing and I don't believe in spraying and walking away, I believe you have to stay and make sure things work as they're intended."
Donaldson said she was confident under her leadership things could be put right.
She was aware people were threatening not to vote for those who oversaw the bus network rollout but said it wasn't a particular issue for the constituency she was standing in, being Porirua and Tawa.
Donaldson said Laidlaw had done a good job as chairman and she was open to taking up the position but that was a decision for after the elections.
"I think he carries a lot of mana and he's of course gone through this difficult year and I don't blame him for not wanting to do it any more, but he's certainly done his service."
Councillors Sue Kedgley and Ian McKinnon are also standing down from the regional council.
Penny Gaylor, Prue Lamason, David Ogden, Jenny Brash, Adrienne Staples, Daran Ponter and Roger Blakeley have all confirmed they're running for another term.
Paul Swain and Ken Laban did not respond to requests for comment.