How to impedance match ur circuit to sweeping excitation from signal generators

How critical is it to always impedance match your circuit to that of the output coming out of laboratory grade signal generators that have standardized 50Ohm impedance?

What is the strategy to ensure you impedance match for a wide band of frequency if you were intending to sweep a wide frequency band and wish to maintain consistent power delivery across a wide frequency spectrum?

Wide band matching may be achievable or not, depending on the kind of circuit. It's generally wanted for high speed circuits but not absolutely necessary. For a detail discussion, you should tell your application and circuit kind.

Any impedance mismatch is usually frequency dependent, and will cause problems in a sweep-frequency circuit.
With frequency-swept generator, a reflectometer is usually used to evaluate the wideband frequency matching. The simplest way is to insert a 10-dB directional coupler with a detector in the coupled output, to observe the reflections from a tested circuit. Then you could adjust a matching circuit to achieve the required wideband matching.