Yes, it's effort based, I'm just saying he tried the same amount when he went at Goku.
You could say that he's not trying at all when he lunges at Goku, thinking he's just another regular Saiyan, with this lowest level of effort being his baseline of sorts.
Yes, exactly. Freeza appears to be putting in the minimal effort against Goku as we can see he is able to rapidly increase his power without effort after the initial exchanges. Logically the minimal effort he showcased previously against Vegeta would be a good place to start. Always assume full power, but in this case, we work in reverse since we know Freeza showcases two levels superior to the one he used initially against Goku.
Maybe he ups the effort when firing his Death Beams, or maybe not even then.
The feats are consistent with each other. Someone who can easily evade and counter a strike then with effort deflecting the Death Beams should indicate Freeza did not change his power. Also, there is no evidence or suggestion that he did. Remember, Freeza's power is rather ambiguous at this time as well.
I think what we're meant to take away, though, is that Goku won a quick exchange against the guy who was just whaling on Vegeta (i.e., the level of Freeza that was just whaling on Vegeta).
Freeza indicated that he was going to use less power and work his way up with Vegeta. Vegeta also offered no resistance and was taken down in a few shots. If there is ever shoukki loss, it would be here. Although I agree with the sentiment in general, I take issue here because we know Freeza showcased three different levels against Goku. So there's only so far we can go but down. He undoubtedly utilized his full power to kick back the Final Burst Cannon, so we know his power only dropped from there.
Also, I just generally assume that once someone ups their effort, they stay there.
Agreed and for 99% of cases I would believe that to be the case. But we have good evidence to suggest Freeza did lower his power considering he states that he would and then we have evidence that Freeza was not using full power against Goku from the get-go, whereas he definitely did versus Vegeta.
You could argue that it makes sense for Cell to not try as hard against Gohan initially, for example, but most of the time we assume that Cell continues to use his "vs Goku" level of effort until he ups his speed.
There is no evidence to suggest otherwise though. Always assume full power is being used in both cases. With Cell, we have no reason to believe he's anything other than full power. With Freeza, we have several pieces of evidence to suggest otherwise.
Freeza (No Hands) > Freeza Warm Up > Freeza Initial vs Goku
We have proof that Freeza was not at his full power in his initial state. We have good evidence to believe that Freeza did use his full power to deflect Vegeta's blast and character statements suggesting that FInal Burst Cannon surpassed his "increased speed" state.