As it currently stands, with the limitation on Soldiery (which is fine, let me note that), I'm basically running 1 Expert, 1 Hard and 1 Trial Roulette each day after the weekly reset. With the bonuses per run+roulette bonus thats.
65+20+?+10(each Trial is different in how many myth you're rewarded for completion of duty, not listing them all)
So 95-110 roughly each day (which is fine) So after 4 days of running Roulettes (440) and maybe one last Hard, or some beastmen dailies you can cap your Soldiery farming for the week, leaving 3 days without them. For most this is a good system, if you only stick to the DF on a daily basis rather than grinding out expert level dungeons back to back it takes you a little over half the week to finish your soldiery for the week.
What about the last 3 days? As it stands now, my log in consists of running beastmen dailies, ventures, logging off. While others have their own play style and desires, such as crafting, doing other jobs, etc.
This idea involves players who cap their Soldiery early, either by Roulettes or as I mentioned earlier by running Coils consistently plus roulettes, it caps quickly.
So with all that said and done. What about adjusting it so that once your capped on Soldiery (which the system acknowledges because it tells you that you cannot receive anymore) it substitutes Mythology for the Solidery instead. For those who are still doing Myth farms for alt gear, or weapons, or crafting materials this would be a nice touch. Or, book farming, for those who may not want/cant do SRs for instance, an extra boost to Mythology after capping Soldiery would be welcomed.
tl;dr - Once you cap Soldiery for the week, substitute the Soldiery and bonus Soldiery you would've attained for Mythology.
Unrelated idea, but regarding Mythology, you could also consider adding a Mythology reward to Leves as well. Perhaps the GC leves that only give seals and exp currently. Since you can spam 99 leves at a time if you build them up, a reasonable amount would be like 5 mythology per turn in. 99*5=495 Or even 10 Myth per turn in 99*10=990.