I was recently forced to confess, in German, that I haven't spoken in a while:
Ich habe seit sechs Jahren kein Deutsch gesprochen
Immediately I realized this was wrong, and felt inclined to say:
Ich spreche seit sechs Jahren kein Deutsch
But that feels like a description of capacity or volition rather than habit. I am struggling to imagine the German way to form this imperfective sense of "the last time I spoke German regularly was six years ago" without fundamentally changing the content of the sentence. I have similar trouble imagining the same construction in other sentences where "not since" phrases are included, for example:
Ich gehe seit Januar nicht mehr täglich joggen