What kind of rate limiting should my RSS parser use for Mangadex's feeds?

[BlackHandScans]

Hi there!

I've made my own RSS parser to keep track of the 100+ manga I'm following. However, my app has been getting a lot of 503 responses lately after I improved it's concurrency. So my question is: how many concurrent RSS feed requests per second do you allow?
I currently fetch the feeds every 10 minutes and parse five feeds at a time with a one-second wait in between each batch of five.

Also should I use a specific User-Agent so you can recognize my RSS parser?

 

[Holo]

Reduce it to 3 concurrent hits, and you should be ok.

 

[BlackHandScans]

Alright, will try that.

Edit: I've tried it and the 503's are gone. Thanks!