How many days does it usually take for customs clearance in the UAE?

Clearance speed will be depend on the ff: Shipment content, value and purpose Destination point (all emirates have diff Customs rules and restrictions) upon checking each details will identify on what time of docs and approval will be required for clearance. Normal import clearance will not take more than1 day if no issues with the Customs.

1 day

the formalities will depend on what you wish to import.
as usual you need some documents to clear it from the customs.
you will get a document called bill of entry.
you need to have four documents normally.
invoice, packing list, certificate of origin and bill of lading.
once your shipment is here, or expected in near days, the agent of your shipping line will send you an arrival notice.
later you can go to the agent and collect your Delivery Order from them by submitting the original bill of lading.
Then you have to approach the customs for passing the Entry bill, in Dubai passing the bill of entry is done through on-line system called Mirsal2 through dubai trade web portal( your company has to register first to do that) .
after passing the bill of entry you have to pay the port charges which is called DPA charges.
that also you can do through on-line.
while doing the DPA charges, you have to put a haulier code to determine who is going to clear it for you.
for example it is a full container and you need to clear it, you have to decide who is transporting agent who take the container from port and deliver to your warehouse.
Then you can pass the bill of entry to the same transporter and they will receive it from the port and deliver where ever you want that container to be delivered.
(they will charge you according to your destination :) and you have option to take quote from different transporters in order to reduce your cost.).
This example is the simplest form of import to Dubai ( in customs terminology they call it import to local from rest of the world) to do this you need to have a local company, a valid importer code, a CDR /STANDING GUARANTEE account to debit your duty and bill of entry charges.
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According to the fiscal policy of gcc and customs law, when a shipment entered inside the country you can keep the shipment for six months with out paying duty and you may pay duty only after the completion of6 months.
in case if your shipment fully of partially exported with in that time you dont need to pay the duty of that.
for that you need to give proof for the customs that the goods are exported.
thats all for today.
all the best

Minimum1 day and maximum2 days if all the shipping documents (Invoice, packing list, B/L or AWB, and Country of Origin)are in line.

Depends on Definition of goods is the goods for TRA, Personal, temp Admission, FZ .
needs approval from municipality,MOH, DPS, etc or not all required Documents Waybill, detailed invoice with Hs Code , COO,