Last year, I used to use 1R50 (The EMT service the OP was asking about) daily, and regularly was held at the signal protecting Hazel Grove High Level Junction, which IIRC is HG21.
This was invariably due to 2H90, the 06:49 Manchester Piccadilly-Buxton service being 2 or 3 minutes late leaving Hazel Grove. On leaving Chinley, I would check on how this train was running (on RTT), to see if my train would be held at Hazel Grove High Level.
In general, if it was on time, there would only be the briefest of delays, or none at all.
If it was 1-5 minutes late, there would be a commensurate wait.
If it was over 5 minutes, the HGR signalman would normally allow us out over the junctions before the Buxton train left the station, so again, no delay.
I also think the section from the Up station starter towards Buxton is fairly long, and is certainly an adverse gradient, so it takes a good couple of minutes for an Up train to clear
There is a signal protecting the Low Level Junction, but this is on the single-line chord section, and possibly the rear of the train may still be fouling the High Level Junction if held here, both good reasons why trains will be held at the preceding signal.