Is the helium good.
What size are you inflating the latex rounds, are they helium quality?
The foils, are they big enough to float, some foils are air filled only.
Are the foils good quality, are you using a rubber or metal to inflate,
on metal you may have a slight burr that is damaging the balloons when inflating.
Are you sealing the balloons correctly, many things can be causing the problems.

I'd better say I do not do décor, just twist.

If you are using good quality latex balloons 11" should float for 16-20 hours without hi float...  9/10" balloon will float for 6-10 hours

lesser quality latex balloons will float for less time

If you are using foils anything smaller than 18" is usually air fill only

We dont buy pure helium anymore (not done for many years), its called balloon gas.. because
1/ they added oxygen to try to save the lives of those that inhale it

2/ BOC (dont know about others) goes to NHS first to cool MRI and CT scanners etc then is collected back and changed to balloon gas.

Pam
xx