Hessenthaler left in-form Eastleigh on Monday to try and save his former club from relegation.
To achieve that, it is felt his squad need to spend much more time together.
In an interview with Kent Online, the new manager outlined his plans - and explained why be traded a promotion push for a battle down the bottom.
He told them: “Dover haven't got off to a great start this year but the chairman wants to go full-time.
"We're going to change that and the players are going to be training during the day.
"I want to implement that straight away. That's got to happen. There are players on full-time contracts so they're not training enough.
"They've only been training two nights a week on their full-time contracts so they've got to be training four days a week plus playing on a Saturday.
"I need to implement that pretty much straight away and the chairman's given me license to do that."
On the move, Hessenthaler added: “It wasn't easy to leave Eastleigh. It took us a little while but we got going with four wins in a row and six games unbeaten.
"It's great to be back though. It's closer to home and the biggest issue for me was family.
"I've got a young granddaughter and a grandson on the way so it played a big part in my decision.”