He's a technician, mentally and physically. Over 5 days, his mental edge and cricketing acumen gives him the advantage over most opposition. If he's worked over in the first, you better believe he will be doing everything in his power to regain that edge.
We know Virat is very calculated in his approach. In the shorter formats, the limited overs and scoreboard pressure can often force him in a position where certain requirements are to be met during different stages of the game. Therefore, even if he knows, changing gears or playing certain shots to meet those demands could result in gifting his wicket away. This, he doesn't have to worry about in test cricket.
Test cricket has its own challenges. But what Virat doesn't have to worry about here is time. With increased overs, Virat can execute his plans with thorough precision, particularly in the 2nd innings setting a target or chasing one.
Coming to the critique over his technical deficiencies. Yes, he was susceptible a year or two ago. Instead of going down the pitch his front foot was going across, resulting in misjudgement of his offstump. At other times, his head would lead but the legs wouldn't follow or they would move too late. He's corrected that. His movements are more synchronized, the head and legs moving simultaneously leading to better alignment of head and foot. He doesn't quite have the muscle memory yet to apply himself instinctively. Therefore he's at his best technically when he's met by a challenge. This gets his brain working and Virat gets fully side-on and all those hours of practice come into play.
Another one of his problems is discipline. He's a busy player, so naturally at the start of an innings, he wants to feel bat on ball. But batting in the top 4, you won't always be able to do that due to lateral movement. Finding the balance between attack and defence is a minor mental issue. I expect a mental genius to find the solution sooner than later.