I find that marking a queen does not necessarily make her any easier to find, in the end, you get obsessed with looking for a coloured spot rather than a queen, fine until there's a supersedure - perfect or imperfect.
I've always used the marking convention, my view is, if I stick to the colours then if I lose a swarm, the person collecting it (unless she is a 'white' queen) can make a guess at the age of the queen - or at least know it's come from a managed colony, not one of these apocryphal 'wild' colonies of 'survivor' bees.
Also, in my case I have enough difficulty in remembering to put my trousers on when I get up in the morning, let alone know what age queen to expect in the colony, the colour of the queen can often have an influence of any decisions I make when I find something in the colony which needs further action (for example, Demarree, A/S, split or blind panic) so I stick with the colouring convention, with fluorescent pink for unknown swarm queens or ones destined for the gatepost at the first opportunity (fluorescent spots do tend to stand out clearly).
I make sure that each queen is marked by the end of the season, any unmarked ones I find at the beginning of the next season I assume are late supersedures and I mark them with the previous season's colour.
Posca pens will last for years ( I have some here in their fourth 'season' now) I'm still uncertain about the Toma ones, they spots do last well but I find the pens get gunked up very easily unless you take care with them. as for longevity of the spots, I've had some Toma marks that have lasted a few weeks and last year I had a colony supersede a queen I reared in 2018 and the red mark was still, albeit a lot smaller, clearly visible.
As for not needing to mark them if you intend on changing them regularly, I think in that case it's even more important to mark them to ensure you know which ones need to be changed.
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