In the first two results from seven Scottish council polls, the nationalists held council seats at Fife and East Ayrshire and still took ground in vote shares from Labour.
But the swings in its favour were smaller than those seen at the May polls and in many other local contests since then.
At Fife (Glenrothes West & Kinglassie), first-preference voting was: SNP 2,235, Lab 1,207, C 234, Green 113. Swing from Labour to SNP 12.9%.
At East (Irvine Valley), first-count voting was: SNP 1,797, C 865, Lab 860, Green 88. Swing from Labour to SNP 5.8%.
In a third contest, the SNP held a seat at Stirling (Stirling East), where the final vote tallies - after transfers - were: SNP 1,388, Lab 1,272, C 352, Green 152.
Further council by-election results are due later from Aberdeen (two seats), Moray and West Lothian.
Swings of between 13% and 25% from Labour to the SNP were recorded in Scottish council by-elections in June and July after Labour was reduced to just one MP north of the border in May.
But local contests last month saw reduced swings of 6% and 8%, while Labour had a success in taking a council seat from the Greens in Edinburgh.
The latest by-elections include four that were prompted by the resignation as councillors of SNP MPs newly elected at the general election: at East Ayrshire, where former councillor Alan Brown is now MP for Kilmarnock and Loudoun; Fife - Peter Grant (Glenrothes); Stirling - Steven Paterson (Stirling); and West Lothian - Martyn Day (Linlithgow and Falkirk East).