I don't understand the concept of '90% finished', applied to anything, much less software or house improvement. It's a human language thing which, in the particular application of a purely artificial and arbitrary invention of something labelled as 'perfective tense', bamboozles us all.
Has the adjective 'complete' any truly useful meaning underneath it? Is, for example, the Mona Lisa finished? Were it deemed 'finished' in, say, 1832, then what of DuChamp's addition of a curly moustache in the early 1900s? The fact that it was executed on a copy is neither here nor there since nothing, in principle, could have prevented his modifying the original. Things exist. Other things act on them. In short, stuff happens. And continues to happen. The imperfective is the only reality.
It's not even as if you need the concept of 'conclusion' (as in premises => conclusion, in logic). Even that damned 'entailment arrow' often seduces one into believing that premises come 'before' (see - it's 'time' language again) conclusions, i.e. that it's a 'time's arrow'. When all you really need is consistency, in the sense that the 'conclusion' and 'premises' can exist - atemporally - in a given universe of discourse, without contradicting the proposed model of that universe. The 'conclusion' can then be just another one of the 'premises', nohing special about it and no earthly reason to position it as the rightmost object of some sequence. Better to employ an orderless set of disjunctive 'facts', none of which contradict any of the others.
Thus is banished the perfective. So you free yourself from the tyranny of process/progress and don't have to 'finish' anything, and can just 'be'. Unless you contradict your own universe, in which case the decent thing to do is to vanish in one of Douglas Adams's puffs of logic.
If I ingest strychnine then I will die. Which is to say, arrowlessly, either I do not ingest strychnine or I will die. Of course if one's given something to play with like 'If the Mona Lisa's finished then Marcel Duchamp cannot paint a moustache on it', things get a tad meta.