Advice? RODI units

You have a top quality system, what you're seeing has nothing to do with it. Its all just plastic housings anyway.
Filter quality matters. Make sure your RO membrane is working efficiently. What is your incoming TDS? What is the TDS after your RO membrane?
The better your water is before hitting your DI resin, the longer that will last.

CR has good water quality. My TDS is <1 after the membrane and I've had DI resin last for a year with 0 TDS output. That was making probably 50+ gallons a week of water.

The other thing is it sounds like your RODI is only running for short periods of time for your ato? That isn't really a good way to run them. The water sitting in the lines and in the membrane is "dirty" so essentially you're constantly blasting that high TDS dirty water into your DI chamber every hour.
The RO filter really needs water flowing across if for longer periods of time to work like it should.

You should really looking at getting a holding tank, and running your RODI for longer periods to fill the tank. Pump your ATO from the holding tank.

 

I have the same system as the op, they have a flush kit, auto shut off, dual TDS meter, pressure gauge. All the bells and whistles you can get with an RODI setup. I didn't use the flush much at all. But again I have pretty good water to begin with and always ran my filter for extended periods of time.
I never worried about dumping the initial water because I would make minimum 35 gallons at a time. So the couple minutes worth of water that went in as the TDS came down wasn't an issue for the volume of water. Making a few gallons or 5, that initial high TDS water is going to be a much bigger deal.

OP if you do get a storage container make sure you have a float valve on the thing. Never trust that you will remember to turn off your RODI because you won't LOL. Everyone without a float valve, or some kind of mechanism that shuts it off has flooded there container. I pretty much guarantee that.

 

It was several times for me before I got smart and fixed my setup. It was all in the unfinished basement so not a huge ordeal to clean up, but one time was overnight.

 

I use an RO Buddy pressure booster which automatically purges for 15 seconds on start-up and then again every 30 minutes

Really the only sure-fire way to keep your water 0 TDS, IMO, is to manually purge/flush for a few minutes before making water. I then prefer to allow the RO water to drain out for a minute before taking it to the DI but that's me, and the RO Buddy doesn't allow you to do that easily (you have to hijack it) so I don't worry about that.

I too have flooded the floor in the storage room on more than one occasion. I set my phone timer now.