The six hour time difference between the UK and Louisiana gave Shelia a lot of grief when we were getting to know each other over Internet. When we started writing the story it caused us problems also. We found our characters still at work in the middle of the night and had all sorts of problerms getting the timing right.
In reality there's a narrow window of time shared by workers in Louisiana and the UK 8:00 - 11:00 am in the US and 2:00 - 5:00 pm in the UK. I know from experience what it's like when someone in the UK gets it wrong and phones you at 3:00 am in the morning!
In the end we built a spreadsheet showing the time in the US and UK to make sure we got times right.
The time zone difference was even worse in the case of 'Stones, Stars and Solutions.' In that book the Triplets go on a globe trotting tour in fast private jets. We had to take into account time zone differences, aircraft speed, range and pilot flight hours. No easy task.
That time difference still bothers us since Shelia's family are all in the US. We often find ourselves chatting to them in the early hours of the morning.