When it comes to hishtadlut (invested effort) and emuna there is a noted difference in the amount of effort one should invest in material vs. spiritual pursuits. Investing time in materialistic acquisitions should be limited. However, when it comes to spiritual matters there is no end to the amount of hishtadlut one should extend; assuming it does not cause undue emotional pressure on oneself.
When asked ‘how much hishtadlut must we put in’ this generally indicates an inability to ‘Let Go and Let G-d’. If we feel we are the ones bringing the results due to our effort then we’ve misplaced our emuna in the commandment of hishtadlut. It is most important not to get emotionally attached to hishtadlut and remember that Hashem is doing everything and doesn’t ‘need’ our help in getting things done.
Hishtadlut is required to the point where Hashem’s intervention is hidden in the realm of nature and does not appear as a miracle. Yet the amount of hishtadlut solely depends on the level of emuna we are on at that time. If our emuna is strong we won’t feel the need to do a lot. However for those of us who are just beginning to build our emuna the more hishtadlut we may feel we need to do.