Modified Experience Checks for Call of Cthulhu

I experimented with an Experience Point rule for CoC, but in the end was disappointed. Then I chose to use this (something similar to HarnMaster's experience rule):

Using skills is often rewarded by GM in the form of experience checks (marked "x" in the character sheet, next to the skill). The GM can award several of these checks at once. The more checks a given skill already has, the less likely the GM is to award more, but there can be at least as many as five (or perhaps even more) checks in one skill, it used for significant purposes, with significant risk, several times.

At the end of the scenario, or when the GM so decides, the players can make their experience checks. For each check the player rolls twice, so for a total of fice checks he will roll a total of ten times. The roll is on a d100, as per rules: the skill is improved on a roll higher than the current skill. The difference from the rules is that no die is rolled for the amount of increase; instead, only one point is added.

I am now trying this in practise, but since it is very similar to HM, it should work well.