I don’t use x3 on my main because I believe I will encounter golden room soon or later and hope it’s flying goblin with additional materials (blessing, solar protection). But I do use x3 on alts that I know I won’t hone them over 1340 for a while.
Only do x3 if you can’t stand doing so many in a row lol.
If you do it x1, there is a bigger chance you will get engraving books, you will hit bonus stages (silver and /or honing protections etc) more times.
That x3 is done for people like you, honestly, that have too many tickets and too little time but that said, if you have the patience, it is better to do them one by one.
since the rewards you get from one cube ticket is pretty small in t3 for the amount of time it takes to finish a cube, i just save up my tickets to do it x3.
I did x1 like 20 times in a row last week trying to get masterpiece #45, still haven’t got it (haven’t even seen the treasure chest room once), will keep doing x1 until I get it.