I don't think anything has changed regarding the pause between program CALLs. I think its due to the difficulty of motion planning across different programs. Normally, certain things are locked when a program is running such as position values. So the motion planner knows that nothing will change.
A potential solution would be if Fanuc would allow you to "group" TP programs. Basically, your CALL instruction would be like a #include in C++ where its the same as pasting the contents of the program into your main program. All programs in the group would be locked when one of them was running.
In my case, this would be helpful to organize the code and make it easier to troubleshoot and unit test.