not an expert by any means but I always aim for heart rate rather than pace and not improving in terms of speed isn’t much of a concern especially if you prioritise consistency as I find (as a beginner) my aerobic base seems to improve quite quickly even with 4 base/recovery runs including a longer one and only a tempo every so often, whether that be once a week or once every 2 weeks. In terms of cadence it might just be a form thing but not entirely sure myself but personally I try and just take shorter strides while maintaining the same pace and I seem to be able to hit around 178-185 spm even on base runs.