Yeah, if your only gauge of performance is "hey, it worked, I guess" -- just put up a 1/4 wave whip or something like that, and leave it be. It's not that you won't do better -- you certainly can -- but you won't
know, and without measurement, any conclusion is meaningless.
Checking signal strength is helpful, but not ideal. It has to be done carefully. Example: an antenna which radiates modestly in the forward direction, but strongly in the sideways direction, might still measure better than a merely "good" unidirectional antenna. Or worse. How? That strong side lobe could take a long path back to the receiver, thanks to reflections in the test area. The test site is critical. An open air test site is preferable, and an anechoic test chamber even better still!
Signal strength indicators are also not consistent. RSSI is an arbitrary scale. Bandwidth is adaptive, and often lazy (i.e., it might not renegotiate for a faster channel, unless it has to). Power level might be adaptive too (i.e., it only uses what it needs), which would *really* throw off your measurement!
So it's very tricky to do, and really needs to have good equipment to get a sound answer. Without that equipment, be very weary of, and careful about, any possible sources of interference: side lobes, reflections, mismatched loads, and dubious measurements. Doubt everything -- yourself foremost, as you are the easiest person to fool -- and also remember that, if it's not falsifiable, it's not science.
Tim