I just think that because it is a bad movie, doesnít mean we canít use continuity of the movie for the benefit of the series.
I donít think it beneficial to pretend the movie didnít exist out of despite. If you can salvage some continuity threads to better things than you should take advantage of it.
It just seems incredibly logical that General Koord was convinced to save Kirk life and they have a gathering at the end of Star TRek V. Thatís a direct continuation of theme for Star Trek VI of peace between Klingon and Federation
Itís a shame that Star Trek V was such a bad movie because skipping V and going from IV to VI still feels there is a gap there. You have Kirk being a given a new ship Enterprise-A at ST IV and then you have in ST VI the Enterprise A is old and retiring. You are still missing a single adventure of the Enterprise-A prior to its retirement. This is also part of the reason why Iím reluctant to just treat it as non-canon never to mention again.
In terms of worst Star Trek Movie - I would put Star Trek 2009 as the worst one although if we ignore Kurtzman era trek and treat it as non-canon.,
Star Trek Nemesis is the worst. The villain motivation in Star Trek Nemesis is completely nonsensical - Shinzon was enslaved by the Romulans all his life and he fought a liberation war with the Remans against the romulan empire, how does that connect with him wanting to destroy the Federation (at least the motivation of Sybok makes kinda sense). There are also equivalent equally bad character assasination (Picard going to pre-warp society and breaking the prime directive)
I will say there are two elements I like of Star Trek V. One is Bones backstory with euthanising his father and then connecting it to the beginning of his angry at Kirk recklessness. The other was Kirk speech about ďI need my painĒ which I thought was effective if it was put in a better movie.
Itís not so much that I think every detail must be consistent across series. However I think that the key plot event/synopsis happened regardless whether the episode is bad or not.
In terms of bad episodes/bad details itís better to recontextualised and ĎexplainĒ rather than ignoring it. I have a few head canon of trying to ďexplainĒ character assasination/plot holes of bad episodes
When the crazy ex-girlfriend Lester state ď Your world of starship Captains doesn't admit women."
I interpret it that Kirkís dedication to being a Starfleet captain doesnít allow room for long term relationship. Hence the motivation of Lester is more of retaliation for Kirk breaking up with her rather than women not being allowed to be Captain (even though Gene Roddenberry explicitly clarified that was the case).
Similar with Star Trek V - Sybok really is mind controlling the crew with his unique technique of mind-melding (we havenít seen it before because it is considered immoral by Vulcan society and of course Spock), itís just that emotional pain is relieve as a byproduct of this technique. Him denying he is mind controlling the crew is an act of self-deception/lie so he can morally live with himself
By post-hoc recontextualising this, you can mitigate some of the damage to canon of those episodes. Star Trek V established that the entirety of the crew of Enterprise are essentially traitors and essentially destroyed the characters of everyone beyond the trinity. I rather have this be ďfixedí rather than ignored because whether I like it or not it was shown in cinemas.