Should I delay Fight or Flight or use hardcast Holy Spirit to force the same Fight or Flight window each time?

No. The “strong” Fight or Flight window of Supplication, Sepulchre, Holy Spirit (1540p) compared to the “weak” Fight or Flight window of Royal Authority, Holy Spirit, Atonement (1420p) is only an extra 30 potency (we’re only moving 120p from outside of Fight or Flight to inside, not creating potency overall, so the only gain is the Fight or Flight buff applied to that 120p, i.e. 120*0.25=30). As a general rule, delaying Fight or Flight or hardcasting Holy Spirit to improve a Fight or Flight window will lose more than it gains. For instance, as the average filler GCD potency is (220+330+460+460+500+540+500)/7 = 430, while hardcast Holy Spirit is ~370p (taking into account the autos you lose from the auto-attack timer being paused during casts), each hardcast of Holy Spirit is a ~60p loss, compared to the 30p gained by going from the worst to best possible Fight or Flight window. Encounter-specific considerations may cause one of these options to be correct but they will almost always be a loss.

Why should I spend the first Atonement immediately after Royal Authority, rather than holding it like before?

As long as you hold Supplication, Sepulchre, and Divine Might Holy Spirit as long as possible, you will still always have three strong fillers for Fight or Flight. Since Atonement isn’t present in the “strongest” Fight or Flight window of Supplication, Sepulchre, Holy Spirit, defaulting to spending the Atonement ASAP will cause this “strongest” Fight or Flight window to occur more often.

Should I prioritize Sepulchre or Holy Spirit in Fight or Flight?

Sepulchre is 40p more than Holy Spirit, so when prioritize Sepulchre when possible. Sepulchre will only push Holy Spirit out of Fight or Flight if entering Fight or Flight immediately after Royal Authority. If Royal Authority lands inside of Fight or Flight, there will not be enough extra GCD slots in Fight or Flight to fit all three of Atonement / Supplication / Sepulchre, and as Holy Spirit and Supplication have the same potency, either Atonement + Supplication or Atonement + Holy Spirit are valid uses of the remaining two GCDs of Fight or Flight in this case.

Why is hardcast Holy Spirit not really 400 potency?

PLD auto-attacks are normalized to 90p every 3s, so with a 1 second cast time (1.5s tooltip cast time minus 0.5s slidecast window), auto-attacks are delayed by 1 second every hardcast. On average, hardcast Holy Spirit is equivalent to 370 potency.

What GCD speed should I use?

2.50 is usually ideal (see the best-in-slot page).

How do I play with a faster GCD speed?

Depending on your speed, it may be possible to get 9 GCDs in Fight or Flight with tight execution and low latency, do this by weaving Fight or Flight late in the GCD. Since you are unable to double weave Imperator after a late-weaved Fight or Flight, you will also need to use Goring Blade or another filler GCD immediately after Fight or Flight, then following it with Imperator into Confiteor combo. Also depending on your speed, attempting to late-weave Fight or Flight every minute will result in large delays over time. At many non-2.5 speeds, you will end up alternating early- and late-weave Fight or Flights in some pattern, and thus alternating between 8- and 9-GCD Fight or Flight windows.

Why 2.50 GCD?

A significant portion of Paladin’s rotation is made up of spells, which aren’t affected by Skill Speed, making the stat very inefficient compared to other substats. Outside of buffing Circle of Scorn’s damage-over-time and auto-attacks, the effect of skill speed is encounter-specific and only results in gains if the filler GCD(s) that it gains outweighs the loss of other substats that buff all of your damage (including your high-damaging burst skills).

I have very high latency (100+ ms), what speed should I play?

Getting 9 GCDs in Fight or Flight is highly execution and latency dependent, on top of being worse than 2.50 in almost all cases. Use 2.50 and avoid double weaving if having trouble with clipping.

Spell Speed?

Spell Speed affects even less of the rotation than Skill Speed does—avoid.