TL;DR
With mixed content cargo wagons the use of the "Item Count" condition can lead to large nested conditions. This could be improved by adding the Everything and Anything signal to the signal panel for trains.What ?
A quality of life improvement: The addition of the Everything and Anything signals to the 'Item Count' signal menu for trains conditions to leave stations. With the signals based on the content of the trains cargo wagons.Why ?
With the addition of filtering for cargo wagons mixed wagons are more practical. This means that you are more likely to wish to control trains based on aggregate conditions of the trains contents.
While there are workarounds they are not ideal.
For example one work round is to add multiple Item Count conditions with each required object however if the condition is complicated then this can severley bloat the list of conditions.
i.e. A train will leave the station based if it has more than 100 of any Science pack and the signal g>1 :
Red science > 100
and G > 1
or Green science > 100
and G > 1
or Blue science > 100
and G > 1
...
With the suggested implementation:
Anything > 100
and G > 1
The other obvious workaround is offloading the conditions to combinators at the stations. While viable this does require the setup of circuits for each type of condition for trains visiting the station and for each station.
While this is obviously a rather trivial problem in that there are workarounds I figured it is a nice little quality of life improvement that may be worth implementing.