The Lestovka used by Old Rite Orthodox is also used to count the number of Kyrie Eleisons (well, technically Godpodi Pomuluis) in the Hours, and also the prayers of St. Ephraim said repeatedly in Lent, and then there is a variant form of Lestovka which I also have, which will have 100 or 200 leather counters, which is used for the Prayer Rule of St. Seraphim of Sarov, which involves saying the Orthodox version of the Hail Mary prayer.
This is very different from the Latin Rosary however as there are no mysteries to be imagined, only the words are said, since as a rule the Orthodox fathers writing on prayer exhibit considerable wariness and concern over the spiritual safety of using the visual imagination in prayer. See St. Ignatius Brianchaninov, et al. I can personally attest this is the case.
I can also attest to the benefits of what
@ArmyMatt said: I have a confessor, a starets or gerons, in this case a priest, and so should every Orthodox Christian.
By the way, I have a small collection of prayer ropes and lestovkas but while some people really need to use them when praying, I use them sometimes but not on all occasions. Also, because the Old Rite Orthodox, such as those lovely people at the ROCOR parish, the Church of the Nativity in Erie, PA, who at one time were priestless Old Believers but were persuaded to return to the fold by someone with ROCOR, I forget who, but basically a domestic missionary, and thus they built an altar and turned the wall of their church into an iconostasis (priestless old believers like those in Woodburn, Oregon, have a doorless iconostasis in that they simply cover the eastern wall of their churches with icons) has different counters on it, these can be used for the purposes that they are used for in the old rite. However, since the lestovka, and indeed the prayer rope, is a primitive computational device like a slide rule or abacus, it can be used to implement a variety of prayer rules, particularly in the case of the Lestovka, where the different counters can be used for counting sets of prayers and individual prayers, but any use of it should be as Fr. Matt said approved by your spiritual director(s).