@activejiggy I don’t think that changing the step counting will affect the battery very much.
Something to realize with the Suunto 5 (I assume this is the non-Peak version?) is the altitude is determined using GPS. If you use any GPS other than Performance mode the altitude/ascent/descent will not show in the watch as 1 min GPS fixes do not allow for determining altitude changes.
The 2, 5 and 10 sec fixes will not improve battery by much, that is why they were not implemented. In the Ambit series these were to provide a reasonable GPS track with some battery savings. In watches that have a compass, Suunto has developed FusedTrack so your GPS tracks are very good even with a 2 min GPS fix.
For the Suunto 5, this watch does not have a compass so FusedTrack is not possible.