Some of the GW2 top-tier items, particularly legendary weapons, seem like rather long-term goals. A guildmate calculated the karma needed for his goals and landed in the low seven digits. Some people will react to this with speed runs and hard work to optimize accumulation. Some will quit from frustration (or satiation, after completing all those speed runs).
Some will quit being Achievers. Like Milne’s river, we shall get there someday. I can farm the events with the best karma/hour and learn the minimum contribution level for a gold medal, or I could just keep wandering around doing whatever catches my fancy. The game will still be here a year from now. Optimization is a kind of fun, but then carrying it out for 20-100 hours is often not. I would much rather do everything once than run the same event twenty times a day.
And if I find one I really like? I can run that twenty times a day. I have a guildmate who really liked one of the arena events and did nothing but two events for ten levels. He had fun and leveled quickly. He found what he liked and stayed with it until he got bored. Good for him.
For my current playstyle, wandering is essential. It will probably remain so until I hit 100% world completion, and then repeat for any new character. Well, I wander in each zone until 80-90%; to fill those last few map symbols, I flip back to Achiever, ruthlessly cull the progression from a zone, then find a new field in which I can smell the flowers. I avoid using waypoints, instead wandering across zones harvesting nodes, participating in random events, and unleashing alpha strikes on hapless monsters when all my cooldown timers are refreshed. Ooh, artichokes!
Bonus tip for improving your achievement score: you get 2 achievement points for every 5 GW1 Hall of Monument points; you also get 2 achievement points for salvaging 200 items (repeatable). If you are backfilling your HoM for the GW2 bonuses (past the cosmetics), unless you intend to wear that title, you will get the exact same bonus faster by running GW2 events. Optimizing GW2 Achievement involves abandoning GW1 Achievement.