Basically, are short rounds realistic? Do they prevent more complicated actions?
First, here is how Mailanka advises to run GURPS games. I totally agree, and this applies for every game with short rounds, BTW.
Here's a link to Mailanka's blog.
However, for melee, I find it better to start with short rounds, and progress to longer ones as soon as both opponents stop to just try and trade blows (usually happens with evenly matched opponents, after they've been trading blows for a while - it's a common saying that fights that don't end fast tend to become drag-out punchdowns). Short rounds account well for the former case.
To simulate the latter, I'd adopt the increasing round durations from EABA v2. (Keep in mind, that's going from a realistic point of view, but the same rule has "narrative" uses as well. Its other use is for more "dramatic" fights with more back-and-forth. That's appropriate for some genres, less so for others). I usually start applying Turn Mods after the 3rd round, and frankly, no fight in the last 5 sessions has lasted over 3 rounds!
Bear in mind, that's for melee. Ranged fights have their own quirks. But right now, due to the setting's specific (and my hobbies), I'm mostly interested in close combat fights.
With that in mind, let's see how to use the "increasing length rounds" and turn mods in GURPS 4e (because I've got better ideas on how to apply them).
Both systems start with 1 second rounds. As the turn gets longer, add the Turn Mod from EABAv2 to your actions, splitting it between your attack(s), defences, Fast Draw actions and allow reloading for expending (as many Turn Mod as it takes rounds in GURPS). Remember the rule that you can't add more Turn Mod to a defence than was added to the attack. Meanwhile, again, the Turn Mod is getting bigger, but it means expending more ammo, and the turn is getting bigger. Refer to EABAv2 (or at least the quickstart) for details on how the rounds increase and what you can use it for.
Done. Yes, it's that simple, IMO.
Now, I still need to deciding how to use the same mechanic for ORC-C (yes, for my Fates Worse Than Death campaign, again). Given the pre-decided number of actions, that might be harder.OTOH, you can and probably should use split actions against a good opponent (or against one who doesn't care about defence). Since the penalty about split actions in ORC-C is big, that's one possible use for the Time Mod. Maybe blind allocation between attack and defence?
I need to think more about it. And maybe for a re-working of the health system of ORC-C, to make results (even) more random.