Bank-to-Bank or Paired EFI injects half the amount of fuel (lb/hr - PW), twice for each combustion cycle (4-stroke engine). Sequential EFI injects the total amount of fuel (lb/hr - PW), once for each combustion cycle (4-stroke engine). So even though the net amount of fuel injected is the same, sequential EFI does it with half as many injector events, by injecting twice the amount of lb/hr - pulse width fuel. The injector duty cycle remains the same but with a doubled pulse width of sequential injection. The increased injector pulse width is why large injectors can still idle good under sequential control but not under Bank-to-Bank control (or Paired). Different injection method but essentially the same amount of fuel consumed.
Sequential injection will always get slightly better fuel economy and cleaner exhaust emissions. Also, according to page 152 of "How to Tune and Modify Engine Management Systems" (book by Jeff Hartman), sequential injection always gains power at peak torque and at peak horsepower. However, for racing applications, the most significant benefit to sequential injection is good idle quality with very large injectors (for the reasons in my quote above), and individual cylinder fuel correction (adjustments).
Another benefit of sequential EFI, is the capability to phase the injector timing, during the intake stroke for best efficiency. Also, since sequential EFI only injects once per cycle, the injector dead time is not doubled (like it is with non-sequential injection, which results in decreased fuel flow and sometimes requires a larger injector to compensate).
(Read "Injection Timing", "Injector Dead Time" & "Individual Cylinder Trim".)
An individual runner intake manifold (multiple throttle bodies) is the one application where sequential injection has the least amount of benefits (power-wise), because the individual runner design gets it's own (isolated) air & fuel supply for each cylinder.
Holley's Untimed Sequential injection strategy still injects once per revolution, but without a cam sync sensor. Untimed Sequential injection (like full sequential), also has the benefit of improved 'fuel rail pressure balance' (pulses), even though it doesn't inject in sequence with each cylinder's intake valve opening. It still injects fuel in accordance to the engine's firing order (programmed into EFI software), however, without a cam sync sensor, it can't identify #1 cylinder.