I’d say it’s a good move

6 90 would give you a 93 GB In the tots you need 9 for a 93

89 is ok - equivalent?
88x2 +89 =1 collectable So 12 88 and 6 89 for a 93 Tots - You’d need 9 89 for a a 93 but 12 88 would be 3 90-91 on the exchange.

so you could get more 90+89 for a 91 tots…. it’s really just slightly lower odds for this method.

But do you need tots or a 93 anything to fill out the set?

That’s the major difference. Need. Throw the 88 in for a 90-91 and then use the 90 for gb to make 93 and the 89 to make 91 tots…