Hi everyone, Helldragon_xd here.
This is just a quick info article from a discovery I had made (I know that I'm not the first person to hybridize ores/materials from different tiers, but just the first one to write a quick guide about it for optimal exp).
Important note is that I haven't figured out the exact decimal levels in which the hybrid method I'm about to show you stops giving exp, so make sure to check your stats each time you do it to ensure that you do not waste ores unintentionally.
Simply put, use 1 ore of equal to or a tier lower for your current Smithing level, and then using 4 ores that are either 1 tier or 2 tiers lower than the first ore. You will then be able to gain the same 0.2 exp granted if you had instead used the standard 5 ores instead of just 1.
For example, if my current crafting level was 34.8: I can use 1 Petal ore and 4 Dusty ores and gain the same 0.2 exp had I used all 5 Petal ores instead.
An important thing to note is that the item created would most likely be from the lower-tiered ore had you utilized the method I'm trying to elaborate on. Of course, in order to gain as much xp as possible while ignoring the end result item, then this is the fastest way.
The same method can be done with Tailoring, in which you use 1 Plant Hide and 4 Tanned Hides to gain the same amount of exp had you used all 5 Plant hides instead.
Note that this method will not grant any exp once you hit the threshold. Once you hit the threshold, you can only advance by using a higher tier ore that's closest to your level, and then 4 ores of 1 or 2 tiers lower than that ore.
The 4 "fodder" ores always cannot be lower than 2 tiers from the tier of the ore that's closest to your Smithing/Tailoring Level. This is something very important to remember and why you should always check your exp after each batch to ensure that you have not hit the threshold yet.
If I happen to find the exact threshold levels, or anything important that's relevant to this topic, I will immediately edit and update this page with everything I have found out.