In my opinion, a worse time is when we get lost. Because after getting some losses, our mental stability will be destroyed and we may make wrong decisions continuously. Finally we lost everything. So at that time we had to close the trade for a while. and there is no worse time when trading. This is our position which may be worse. But once that is closed on Friday and opening Monday, I think this is the worst time on the forex market. Actually this is not trading time but is applied to positions that have been opened on Friday !!