it comes down to how well you are at filling out the online application without mistakes (which results in a cancellation) with the correct documentation (so they don't have to email you for more documents) and when you apply (so you don't get hung there over the weekend)
As a general rule if you apply online say sunday, show up at the consulae monday morning with the QR code confirmation to pay in cash for the visa you should have the approval by wenesday
They're pretty fast 3-5 business days on regular (Non-O, Non-B, Non-ED, Tourist) visas
Don't forget to upload your visa/entry stamp to Lao to show you're actually in the country
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