My goodness. Sure--I will give you the NEC code section. It is 210.19(A)(1) that specifies this 125% oversizing of the conductors for continuous loads. Here is the wording of it:

"210.19(A)(1) General. Branch-circuit conductors shall have an ampacity not less than the maximum load to be served. Conductors shall be sized to carry not less than the larger of 210.19(A)(1)(a) or (b).

(a) Where a branch circuit supplies continuous loads or any combination of continuous and noncontinuous loads, the minimum branch-circuit conductor size shall have an allowable ampacity not less than the noncontinuous load plus 125 percent of the continuous load.

(b) The minimum branch-circuit conductor size shall have an allowable ampacity not less than the maximum load to be served after the application of any adjustment or correction factors."

It is section 220-10 that has the mirror wording of this same provision of the 125% oversizing for selecting the overcurrent protection device (circuit breaker). The breaker and conductor size both must be 125% of the continuous load. In the case you are talking about, 24A continuous draw must have 125% of that rated for the breaker and the wire size = 30A. So that is why you can use the 10 gauge wire, for a 30A rated circuit, but it cannot use more than 24A draw continuously.

If you were going to have a 30A continuous draw, the breaker and wire must be 125% sized to 37.5, which needs to be rounded up to 40A rated breaker and wire, which cannot be 10 gauge for the 60 or 75 degrees C categories. It would have to go up to 8 gauge wire.

Here are plenty of articles that talk about this.

https://www.ecmweb.com/content/article/20885567/sizing-continuously-loaded-conductors-made-simple
125% Continuous Rule - Panelboards
NEC - when to use Continuous Load rating (X125%)
Continuous Loads Decoded | Explanation of the 125%
210.19(A)(1) Conductors Minimum Ampacity and Size.
Sizing Conductors, Part III