It's what makes engineering (of any sort) so compelling - the innate desire to get it "perfect" for one's own satisfaction (even if it is something others would regard as trivial). This is what set the engineers (of old) at loggerheads with the bean counters, and what brought the "cost plus" defence industry to its knees (once the govenment money started insisting on "fixed price"*).
Engineering management had a "shoot the engineer" brief - which means cut him off tinkering as soon as it is good enough to do the job. Engineers got around this by making sure it was missing some vital element until the very last moment of being satisfied with the product. None of this is relevant to the amateur, who is by definition doing it for the love of it, but suffers from the risk of unfinished projects when you get bored, something more interesting comes along, or something else demands your time. Engineers now are expected to be businessmen as well, to manage their performance to the agreed costs and timescales, and to shoot themselves when the time comes.
* Fixed price defence contracts have their own down-side. They mean that a huge effort goes in to the bidding stage when the bidding companies or consortiums have to work out exactly what is needed to meet the requirement of the contract on tender, and management forces the contributing departments to commit to costs and timescales for their respective contributions (and then usually cut them in half before bidding to try to bid a "reasonable" price**). That process is replicated in all the bidding organisations, and only one gets the contract, so all the others have run up huge overheads which have to be recovered in the next won contract. Once the contract is awarded, the end product is fixed by the terms of the contract even if it is only due for delivery in ten years time (and even though developments in technology will have made the contracted product obsolete before delivery). Any attempt to modify the contract in progress will be viewed as a contract change and only agreed to with huge penalty payments - so that the purchaser has little choice but stick to the original agreement.
Then there is the well-known phenomenon "conspiracy of optimism". The companies bid an optimistic price in order to secure the contract; the MoD defence chief wants his new bit of kit so turns a blind eye to an optimistic bid going through to the Treasury paymasters. The paymasters don't get a pat on the back for rejecting a contract as being unfounded, so it gets through them too. Then many years down the line (when the original personnel have retired or moved on), the winning company comes back and says "sorry, if we try to complete this contract for the agreed price we will go bust and you won't get any kit at all", so the government has little choice but either to throw away the stage payments they have already made, or agree to a new price for completion.
All in all I think "cost plus" (a company doing work was given whatever it cost as it went along, plus an agreed profit margin) was a better way of doing it: state-of-the-art could be reviewed on a regular basis and incorporated into the requirements, the only issue being making sure the delivery date didn't drift off into the distance. Sure, it costs a lot to do things that way, but at the moment it's costing a lot not to do it that way.
** I've seen three sides of this. As a design engineer the design process always takes longer than has been allowed (no matter how much you inflate the estimate because of past experience, Management always knock it back again). As a test engineer, the test budget (time and cost) gets eaten into by the design over-run, so there is even more pressure to cut corners. Then there's pretty much the last stage of the chain (by which time all the money has run out) - Tech Pubs. In Tech Pubs... let's just say "I know my place".
Don't even get me started on "commercial off-the-shelf"...