But see, it works both ways. If a judge can unilaterally block the president from exceeding his authority, a judge can equally well block the president from exercising his authority. (There is no magic black letter printing on executive orders that is within his authority and red letter printing for those that exceed it. In fact, this is exactly what these court cases are about.)
So either a judge can block orders that exceed the president's authority and orders that are within it, or the judge can block neither.
Sure. And if their judgment is deemed incorrect, it will be overturned on appeal. If the matter is urgent, appeal will be expedited. That's how the system works. You can certainly argue that we need more courts to handle the current workload, but let's directly address that issue rather than curtailing the injunction power to reduce the work.
Bear in mind that this was a case where the multiple courts who considered the issue were unanimous in their opinion that the President was very likely to lose on the merits. Exactly the kind of case where there should be an injunction.
These weren't being used in that manner though - Trump was winning on appeal, then a second court would issue the same injunction, forcing him to go through the same thing again. This ruling was needed to stop the courts from abusing their power.
But that's fine because the executive can appeal and is in a much better position to do so, and it makes far more sense for the law to be consistent than to only benefit those with the power and time to fight back.
Since when did we start arguing that executive power must be unchecked for fear of it being slightly inconvenienced?
So either a judge can block orders that exceed the president's authority and orders that are within it, or the judge can block neither.