No, because fleets will move 1/5 as far in a single sub-pulse. An example might help:
Consider a fighter squadron at 10,000 km/s attempting to close with an enemy cruiser at 5,000 km/s. The fighters are armed with 10cm railguns @ 30,000 km range. Suppose the fighters are approaching from the stern of the cruiser and are 35,000 km away, just out of range:
Fig. 1: Situation at the start of a 5-second increment
FTR -----> 35,000 km CA -->
If the fighters and cruiser continue along these trajectories, the fighters will close to 10,000 km range and be able to fire their railguns. If the cruiser has a lower Reaction score than the fighters, that is what will happen.
However, if the cruiser has a higher reaction score, it can evade the fighters. This is because the fighters will try to anticipate the cruiser's movements and move to where it will be, rather than where it is at the start of the increment, thus the fighters will move forwards by 50,000 km in a 5-second pulse, temporarily placing themselves 15,000 km in front of the cruiser.
Fig. 2: Situation partway through a 5-second increment, after the FTR moves but before the CA moves
CA 15,000 km -----> FTR
Due to its superior Reaction score, the cruiser is now able to evade the fighters if it has anticipated this, by moving in the opposite direction (I believe a Follow order with a sufficient minimum distance would do this automatically):
Fig. 3: Situation at the end of a 5-second increment, after the FTR and CA have moved in succession
CA <-- 40,000 km -----> FTR
The cruiser thus remains outside of the fighter maximum weapons range and likely can fire on the fighters with its longer-ranged weapons. This state of affairs would continue indefinitely (or until the FTR are destroyed) unless and until one party to the combat changes their orders, such as the FTR being given a minimum distance criterion or a reduction in speed.
If the minimum sub-pulse is only one second, then this behavior can still happen but the difference in range is only 1/5. The fighters might overshoot the cruiser but by at most 15,000 km which is well within their weapons range.
Now, we can have discussion over whether this 5-second minimum reaction time is "realistic" or not (I think it ultimately is up to the player as every RP setting differs), but in pure gameplay terms it is mostly just an annoyance for the player which requires odd workarounds (closing to point-blank by giving a minimum distance criterion is unintuitive to say the least). With the 1-second subpulse the abstraction of "real-time" combat is maintained even with the necessary concession of discrete time increments to allow computation.
You can see similar behavior in other situations, e.g., in a stern chase while trying to maintain the right sniping range for your own beam weapons to outrange the enemy. In my 1.12 AAR I recount several battles of this sort and maintaining range is always the most challenging aspect. This change to subpulses in 2.0 would make that part of the battle significantly smoother and less annoying.