A couple of things I've noticed...
Remember that there's not an "official" annealing point, as such. There's an annealing range, which is anywhere between the strain point and the softening point (850 and 1060 respectively for effetre). Any temperature in that range can be an annealing point. Generally speaking, the lower the annealing point, the longer the T3 soak.
The strain soak (T5 on the chart) is a really important soak. You'll notice that the chart shows the strain soak takes place very slightly above the strain point of the glass, and with good reason. It gives the glass molecules a chance to catch up, temperature-wise, and find that final relaxed state before being "frozen" as the temp drops below the strain point.
If you're doing a strain soak below the strain point, it's not doing what is intended. A strain soak below 850 (for effetre) does nothing for the annealing process, the glass is already frozen by that temp and nothing is accomplished. It's pretty much a waste of time and electricity.
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Passion is inversely proportional to the amount of real information available. - Gregory Benford
So come up to the lab and see what's on the slab...
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