Most HTTP libraries ship with a default timeout somewhere between "none at all" and "way too generous," and most proxy-routed traffic inherits that default without anyone deciding it on purpose. Here's why that default is almost always the wrong number, and how to actually pick one.
Why proxy traffic needs different timeout thinking than direct traffic
A direct request to a target has one network hop's worth of latency variance. A proxy-routed request has at least two: your connection to the proxy, and the proxy's connection to the target. Residential and mobile proxies specifically add real-world network variance on top of that — you're routing through a consumer ISP connection, not a datacenter backbone, and that connection can have genuinely variable latency for reasons that have nothing to do with anything being wrong.
Treating proxy-routed latency variance the same way you'd treat direct-connection latency variance means your timeout is tuned for the wrong distribution entirely.
Too short: the failure mode nobody notices until it's expensive
An aggressive timeout (say, 3-5 seconds) tuned for direct-connection speed will treat a large fraction of genuinely successful-but-slower proxy requests as failures. This is expensive in a specific, sneaky way: you retry a request that was actually about to succeed, burning an extra request against your pool and against the target, for a "failure" that was never a real failure — just impatience.
Too generous: the failure mode that wastes resources differently
A very generous timeout (30-60+ seconds) means a genuinely dead or hanging connection ties up a worker/thread/connection slot for a long time before failing, which throttles your actual throughput far below what your pool could support, especially under concurrency where each hung connection is blocking a slot that could be serving a request that would succeed immediately elsewhere.
A better starting point: measure your own distribution, don't guess
Before picking a number, log actual response time distribution for successful requests through your specific proxy setup, against your specific targets. Set the timeout at roughly the 95th-99th percentile of successful response times, not a round number that sounds reasonable. This means:
successful_latencies = [collect over a real sample, e.g. 500+ requests]
timeout = percentile(successful_latencies, 97) * 1.2 # small buffer above p97
This will almost never match a "sensible-sounding" default like 10 or 30 seconds, and that's the point — the right number is specific to your proxy type, your target, and your geography, not a constant that applies everywhere.
Different timeouts for different phases of the request
A single timeout value applied to the whole request lifecycle conflates two different things worth tuning separately:
Connection timeout (how long to wait to establish the connection through the proxy): usually should be shorter and stricter — a connection that's slow to even start is a stronger signal of a genuinely bad IP than a connection that's just slow to finish
Read timeout (how long to wait for the response body once connected): can reasonably be more generous, since a slow-but-completing response is a different situation than a connection that never even opens
Splitting these lets you fail fast on clearly-bad connections while still tolerating legitimately slow-but-working ones.
Timeouts as a pool health signal, not just an error-handling detail
Track timeout rate per IP over time the same way you'd track ban rate. An IP with a rising timeout rate (even without outright failures) is often an early warning of degrading quality before it shows up as a hard failure — this is exactly the kind of signal that gets missed when timeouts are treated purely as "did the request work or not" rather than as a graded quality metric.
Getting this tuning right is a big part of what separates a scraper that runs reliably in production from one that looks fine in a quick test and then falls apart under real load — this is the kind of thing we spend real engineering time on when helping teams integrate SotaProxy into an existing pipeline. If your timeout values are still whatever the library shipped with by default, that's usually worth revisiting before anything else.
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