10-15 ops is a lot of workers to recover.
F2 is a good example for me right now. I joined the world at tick 11. I was alliancless till tick 40 and my conquer wouldn't liberate me till tick 55. Once he liberated me (When I place I like to place out the way where I can expand more solo) I built 3 ops straight away. A couple ticks after I built another 6 and just flew my spams right across the map (It helps that I started boosting blues at tick 50 I guess, can't say it's possible without boosting). At tick 100 I was in the top 50. After tick 101 I was in the top 10. By tick 200 I was rank 1 and have been competing for rank 1 ever since.
(and this is me playing after I said I quit BD. So I actually go out and miss ticks, not nearly as active as I normally would be)
Like I said, it's all about the rewards you can make from building the ops. If you can capture 3 ops and afford to raze them, you get your workers back for the one op. If you only manage to get 1-2 ops you can raze, but if you get a couple conquers, then these will replenish your workers over time. Even if you manage 1 conquer, 1 razed op, 1 mine/well, you will get your workers you spent back in less than 200 ticks (and your income will be increased from the conquer, well/mine, and res from razing the op) and this is much less than I'd like to capture from building one op.