I do a few things to keep my market clear.
First, in the morning I complete all dino dropping events except for the last battle. I only finish the last battle when I have a slot in the hatchery for it. (Rare/common in the first spot only and short running super rares. The long running super rares maybe be in the first slot, but sometimes will go elsewhere.)
If I don’t have any slots open at the end of the day, I’ll buy out the dino that is cheapest per hour (typically the most expensive one). I won’t buy out dinos that end in the morning when I battle, as it is an easy swap.
Tuesday mornings, I try to clear everything out of the hatchery as well as that day’s worth of event dinos that are Legendary and above.
I’ll also use the schedule to plan out when I’ll need more slots for the next day and buy for DNA dinos that’ll work with what I’ll need the next day.
Lastly, as I have extra slots, I’ll coins-> dino trade to fill them.
Recently, I’ve been doing coins->ceno and getting 80% Smilodon. I’ve hatched 9 or so of them now. The rest I’ve traded for DNA or DB, whichever comes first. (I’ve yet to get an LP offer on one.) I get 2K-4K DNA for them or 500DB. I prefer DNA as the AP fossil does similar for DB, but like I said, I take the first offer for DNA/DB (or LP if that ever happens).
Lastly, I only grind PvP modded if I have an open spot in the hatchery. (I use to grind PvP, but my extra spin is often broken, making it not worth it.)
It all comes down to a little planning. If you keep your market clear, you should even out on DB in vs out on speed ups.
If you keep your mods clear, you should be increased in DB if you aren’t speeding them in other ways (like dino cool downs).
I’m not DB rich, but I need the dinos at this point.