[time-nuts] Data collection cycle -- multiple sources to one counter?

[John Ackermann N8UR]

I want to monitor all my atomic devices over the long term against GPS. 
Rather than devoting one counter to each source and gathering a lot more
data than is useful, I'm going to use a GPIB-controlled coax switch to
route the 1pps from each source into the counter START input.  That way
I can alternately read each source for X minutes against GPS.

My question is whether there is an optimum "X" for the time to dwell on
each source.  I've been thinking that 15 minutes might make sense.  That
means I'd start with device A, average it against GPS for 15 minutes of
1pps samples, record that to the log file, then switch the input to
device B, dwell there for 15 minutes and record, then to device C for 15
minutes and record, then repeat the cycle.

With three devices, that would give me averages of 900 readings and a
tau of 45 minutes.  Seems reasonable, but I suspect a lot of labs do
something similar and I wonder if there's tribal knowledge of the
optimum cycle.

Any thoughts?

John