GO trains can enter platforms at nearly 100 km/h and still stop at the end (a distance of about 320 metres) and it's pretty common for them to enter going 70-80. Adding a 15 mph (24 km/h) restriction for 2300 metres is an enormous time penalty regardless of where it is relative to stations.
An electric regional train can accelerate to 75 km/h WITHIN the station:
The distance from Oshawa to Thornton Corners is about 1400 metres (which would be by far the closest spacing on the network).
View attachment 707042
Here's a clip where I compare the speed of O-Train Line 2 (with a 55 km/h limit) and the REM (with a 100 km/h limit) with a stop spacing of about 1.5 km (1450m for O-Train, 1504 for REM).
The REM trains reaches 85 km/h and AVERAGES 55 km/h between those stations. The O-Train takes 49% longer, primarily due to the 25 km/h limit in stations and 50-55 km/h limits between stations.
Now just imagine how slow the O-Train would be if the 25 km/h speed limit also applied between stations! Actually you don't need to imagine, because you can easily calculate that 1500m at 25 km/h is 216 seconds. So even with infinite acceleration and deceleration, the (G)O Train would take 118% longer than the REM. And that's not the whole slow zone either - the speed restriction will continue for another 500 metres beyond the station, plus the length of the train, so about another 850 metres.