What early strength is actually buying you
The point of a high early mix is time, not final strength. A slab built with one still lands at roughly the same design strength weeks out. What changes is the curve on the way there, so a footing can take a form removal a day sooner, or a patch of driveway can be walked on before the standard schedule would allow it. That is useful when a schedule is genuinely tight, cold weather is slowing everything down, or a section has to reopen fast.
Ordering it because the schedule is tight, not because the mix is
The mistake is reaching for a high early mix as a general fix rather than for a specific reason. It costs more than a standard mix for the same strength, and faster setting cement generates more heat as it cures. On a thin slab that heat dissipates without trouble. On a thicker section, a foundation wall or a mass of concrete poured all at once, that extra heat can build faster than it can escape, and the difference in temperature between the hot core and the cooler surface is what drives thermal cracking, a separate problem from the ordinary shrinkage cracking a slab already has to manage.
A crew that is not ready for the faster clock
A high early mix does not wait for the finishing crew to catch up. It sets on its own faster schedule regardless of how many hands are on site or how far along the pour is. A crew planning around a standard set time and working with a faster mix runs out of the open window before the surface work is done, and rushing a finish against a slab that is already stiffening is how you get trapped tool marks, an uneven texture, or a trowel that tears the surface instead of closing it.
Not a substitute for what an accelerator does
High early mix and an accelerator admixture solve overlapping problems from different directions. The mix changes the cement itself at the plant. An accelerator is added to speed a standard mix at the batch or the truck. They can be asked for together on a genuinely cold pour, but ordering one when the job actually needed the other is a plant conversation worth having before the concrete is booked, not after it arrives.