Recurring diaper rash

TinaL99

Stella keeps getting a diaper rash.  We've tried different wipes and diapers, but it hasn't helped.  Day care changes her about every 90 minutes as opposed to the usual 2 hours (unless they realize she needs it before 90 minutes).  The rash will clear up for a day or so with the Aquaphor we've been using, but then 1 poopy diaper will bring it right back.  Now the eternal question:

Is this normal?