Yes, SUMPRODUCT
is an option - say you want every 5th cell starting at A2 (i.e. A2, A7, A12 etc.) you can use this formula to count instances of "text" in those cells (possibly within other text)
=SUMPRODUCT((MOD(ROW(A2:A1000)-ROW(A2),5)=0)+0,ISNUMBER(SEARCH("text",A2:A1000))+0)
change the 5 to whatever n you want - it always starts with the first cell in the range if you use this syntax.
The ISNUMBER(SEARCH
part gives you the equivalent of a "wildcard" search (you can't use actual wildcards here)
update
If you want the equivalent of "text*" then use LEFT function, e.g.
=SUMPRODUCT((MOD(ROW(A2:A1000)-ROW(A2),5)=0)+0,(LEFT(A2:A1000,LEN("text"))="text")+0)
and RIGHT can be used for the equivalent of "*text".
IF you want the equivalent of "t?xt" that would be trickier. The SEARCH function in the first formula will allow you to search for "t?xt" but that would be amongst other text so if you want the entire contents to be "t?xt" you could add another check, e.g.
=SUMPRODUCT((MOD(ROW(A2:A1000)-ROW(A2),5)=0)+0,ISNUMBER(SEARCH("t?xt",A2:A1000))+0,(LEN(A2:A1000)=4)+0)
That will only count cells which contain "text", "toxt", "t5xt" etc. but not "text2"