The other day, I mentioned that my players have occasionally suggested reducing the effect of Great Haste. Here are some ways you could potentially do that.
Instead of Altered Time Rate, have the subject of the spell gain one of these lesser effects:
Double the same Maneuver Only. You still get two consecutive turns. However, you must take the same maneuver twice.
Double Your Abilities: You get one maneuver. However, you also gain the following:
Your Move is doubled. If this raises your Move to 11+, you also gain another Step.
Your number of attacks is doubled. You can still only split one attack per turn into a Rapid Strike or Dual-Weapon Attack.
If you choose to All-Out Defend, you gain both +2 to one specific defense and Doubled Defenses. Move limitations still apply if you choose something other than Dodge.
If you choose Concentrate, your Concentrate maneuver counts as two seconds. You are still limited to one spell per turn.
Overall Bonuses: You get the following:
Your Move is doubled (as above.)
You gain Extra Attack 1.
You gain +2 to all of your Active Defenses (alternatively, +2 to Dodge and multiple defense penalties are halved. Defenses already at -1 cumulative drop to -1 per two defenses.)
None of those has been playtested, but I think they're all worth exploring to some degree. That is, if you agree that Great Haste is too valuable and too effective but still like the idea of a speed-based buff.