It is safe to use diapers all the time.
Using diapers all the time on your baby or toddler is safe as long as you clean them up during diaper changes and change the diaper often enough.
Even when a baby or toddler has a wet diaper they should be wiped down as some pee can be on the skin which can lead to rashes.
Babies and Toddlers who are not potty trained should wear diapers all the time until they are potty trained.
However it is okay to allow the baby or toddler some diaper free time for around 20 to 30 minutes or so after every few diaper changes.
This can allow the child's skin to air out to prevent diaper rash as well.
As long as you allow the child's bottom and diaper area to air out and keep the child clean and don't let them sit in a wet or poopy diaper for too long then it's okay for the child to be in diaper all the time.
Diapers are meant to be worn 24 hours per day and lots of babies go all day and all night wearing diapers except for when being bathed or changed etc.
Just make sure to clean the baby or toddler up when they are in diaper and keep them clean and they should be just fine.
Also use diaper rash cream especially at night.
Use a good absorbent diaper as well to keep the baby and toddlers skin dry and to help prevent diaper leaks.