I haven't had my shrimp deliveries get delayed personally but as the Mod here for many years, I have read every post here. So I've read many stories of late deliveries. And yes, there has been many times where shrimp have been delayed in the post. You'd understand if you lived in Australia, cause Austpost.
7 days or longer is possible for shrimps, BUT!
The BUT is dependent on temperature. If temps are high, like in above 28degC, shrimps are less likely to survive being trapped in the shipping bag for a week.
Also, I quoted your comment above because, that is not the best way to handle shrimp (or fish) that have been in shipment for a long time. The "slowly, slowly" method of drip acclimation to match your tank water needs to be avoided this one time. The water these new shrimp will arrive in will be full of ammonia. Every minute counts. We need to get them out fast!
Do this instead.
test the water they came in for pH, GH, KH, TDS and temps.
Match the new water exactly to these parameters.
Net the shrimp into the new water (matched to the water the came in) directly as soon as possible.
The point here is to get them out of ammonia rich water as quickly as possible.
Then, you can start looking at acclimation to your main tank parameters.