Based on the timings in ToT, despite NRS/QLOC trying to obfuscate (read: confuse) everyone with its naming conventions of the new Ko-op, Tag Assist, Premier, Heroic and Rapid towers, the three-hour time interval hours is still the best indicator of when new towers with worthwhile rewards to unlock lies.
Just need to remember: 1500GMT, 1800GMT, 2100GMT, 0000GMT, 0300GMT, 0600GMT, 0900GMT, 1200GMT, and back to 1500GMT.
1500GMT = daily reset, RAT resets, Premium Shop resets. All these means possible new towers, although they're mostly repeat towers at this time. Premium Shop resets means possible new gears/skins included in Bundles available for purchase, although lately there's far and few in between.
1800GMT = NRS/QLOC possible chosen time to release new towers with rewards. Less often happening here than on GMT+6. Possible nuisance for myself as it's in the wee hour of the night, but with time-traveling, everything's attainable again. I usually skip this hour and just wake up, have my morning coffee and open up Reddit, see what chirpy Redditors posts on the official Reddit about what new towers has been up while I was asleep, dial the time back, and just do the towers that I missed.
0600GMT = has been NRS's favorite time to release new ToT towers with unreleased rewards. Why? Because it's way early past sleeping time in the US, and early(or late) enough in Europe to catch reward hunters offguard for not "staying up" for the tower. Hence why you see lots of grumblings in Reddit and Discord on how they missed these towers (usually only lasts 2-3 hours) and its rewards and constant hopium that it'll recycle/reappear. Lucky for Oceanic and East Asian folks, this is lunchtime. More than wide-awake and alert enough to see the changes in ToT and to do them. :p
I'd say it's rather lucky for Australians and New Zealanders and South East Asians and East Asians in general, because due to this CURRENT release patterns based on time periods, by NRS/QLOC, it favors them more versus the Europeans and Americans. Although it doesn't really matter if you're on PC and can time-travel, or on PC and uses the unlocker. The often-thought neglected PC version (compared to the other three consoles) is actually low-key subconsciously the best version of this game, if you think about it. Sure, updates may come a week late, but easily caught up back again with using the unlocker. In fact I got caught up with the one-week late release of Terminator on PC (versus the consoles) around the 4th day after patch drops. You can sneak past into the future to see what's coming, and plan your days ahead around it if necessary. You can travel back in time to do the towers you miss.
Speaking of time-traveling, I just skipped ahead towards GMT+15 today, pretty crucial one since all FIVE of the rotating towers resets at the same time at that time (GMT+15). Nothing much really, and all rewards available are already completed/unlocked for those who used the unlocker right up until now.
At 1500GMT today, here are the changes that will happen:
Ko-op tower = Geras
Heroic tower = Kano
Premier tower ("Engulf in Flames") finally changes to Scorpion, all rewards already unlocked.
Turns out to be the new "Team Raid" mode tower. Long story short, it's time-wasting and overly relying on other team member to carry their weight in the match.
Rapid Tower = Random Liu Kang. *who cares about these Rapid towers anymore, they're useless*
Tag Assist tower = Random Sub-Zero & Scorpion. *another "who cares" tower*
My only hope is that Premium Shop has new Bundles with unreleased gears and skins slipped in these Bundles, current rotation in there is so dull and boring.
Case in point: look at how dead Reddit and Discord are now at this time. Perfect time to release new towers unsuspectingly, NRS/QLOC.