Here in KY, I hunt almost exclusively with a lever action...actually, 5 of them, all Marlins: .30-30, .44 Mag, .41 Mag, .35 Rem, and a .357 Carbine. All of them now wear scopes, four mounted with the old 2.5 x Leupold 7/8" tube Alaskan model, and one (the .35 Rem), with the same Leupold but in 4x. I've always sighted in my iron sights before mounting a scope, and in the case of the .357 Marlin Carbine, I also have a Williams Foolproof receiver peep sighted in. The scopes became necessary when my eyes passed the 72 year mark...damn, I miss the easy feel of an uncluttered Marlin lever receiver cradled in my gloved hands.
While I've never needed the back up sights due to inclement weather, fogging of the scope, or a hard fall that ruined the scope's sighting in, I've kept the ability to use the open or peep sights if needed by first sighting them in prior to scope mounting. A little insurance is a good thing, don't you think...or is it a case of a belt plus suspenders?
The pic below has four of the five Marlins. From the top, the .30-30 Texan with a 3x Weaver 1" tube (note the difference that the smaller Leupold 2.5x 7/8" tubes on the two below it...a more compact setup). The 2nd one down is an 1894S .41 Mag, the 3rd, believe it or not is a 336 in .44 Mag with after market checkering done, and the last is a Marlin 1894CS wearing a William receiver top peep....this one is an especially nice set up, keeping the lever's narrow, easy to carry receiver, but up grading the sights with the peep, and cutting out the weight that a scope would add. JMHO, YMMv and probably does
Best Regards, Rod