It is streamed transient data from a radar head and it is not worth the overhead to put timestamps on the data; so it is actually better to just discard rather than buffer the data. But communications designs tend not to like discarding data. The amount of data is often underestimated an SSR sweeping a target at 100 miles will have more than 10 interrogation responses a primary radar (dependent on PRF) will also have multiple hits/reflections on most targets so you can lose a few without problem.
I expect considerable advances in surveillance / position reporting in the next few years that will make most of what is used (and even planned) now obsolete.