Actually the way the timegates work can't create loops. You basically go back a set number of years, so if it's 8:00am on July 20, 2022 and you go into a timegate, it'll take you back to 8:00am on July 20, 600AD. Then if you spend, let's say five minutes there, and reenter the timegate at 8:05am on July 20, 600AD, it'll take you to 8:05am on July 20, 2022.
It's a weird thing in Chrono Trigger, the idea that even with time travel at your disposal, you can't go back and fix things you goofed. I don't think many time travel stories deal much with inevitability and the inability to change history except for maybe The Time Traveler's Wife.
I know this is way more than your comment warranted, sorry. LOL