Some half decent signalling at Arnos Grove and, to some extent, Cockfosters would help. The current design simply doesn't cope with an intensive service for various reasons, plus the design of the Arnos Grove train crew depot being rather remote from the platforms introduces fragility when things go wrong. It didn't help that Arnos Grove was made into a rather too large 'superdepot' in the late 90s (can't remember the exact date - may be slightly more recent than that?) but the recent opening of a new depot at Cockfosters should have eased that issue a little.
Unfortunately it hasn't; most second half pickups after meal reliefs are still at Acton, then Arnos, with only a handful at the other two. So you have the situation where almost all of the work is still being done at the old superdepots, but with fewer duty managers and spares to assist.
All too often when they want to reverse a train short at Oakwood or Arnos to get it back on time it isn't possible due to the crew relief being at Cockfosters.
When there is an emergency timetable Cockfosters and Northfields send all their drivers to Arnos and Acton respectively, so again the new depots are of no assistance as you lose time.
I shouldn't envisage 30+tph being too difficult to manage between Arnos and Cockfosters if stepping back was implemented and the trains run in ATO. After all, the Victoria line manages 36tph with just two platforms, although with the overrun tunnels can achieve much faster speeds into the platforms. 24tph can be achieved somewhere like Stratford already, and Arnos already copes with a reverser every 10 minutes with quite long turnaround times. Only issue is that it is oversupply of services to the end of the line, like they are finding on the Jubilee.
