Most of the articles that advise against having multiple funds is based on fees and duplicate insurances.
Industry funds have small weekly fees, with remainder of fees based on size of super balance. Rough maths shows negligible difference for two funds in fees vs one in my situation since the largest part of the fee is based on the funds invested.
Funds often auto opt you into insurance (many people dont look to see if its needed), but if you opt out like i plan to not a factor.
I already have 2 funds, both have investment options that are supposedly the same but last year one did well and wont did badly a 5% difference between the two. In prior years they were very close (maybe only a decimal place different), if id chosen only one and it was the wrong one id have lost more.
So in addition to having more guaranteed against company failure (no idea how easily it could happen), it also spreads performance risk.
Not an approach im recommending for others just what has worked for my situation.
But im still researching.